Klinik Kesehatan dr.Bobby M

Rectal Cancer

Introduction

Background

Colon and rectal cancer incidence was negligible before 1900. The incidence of colorectal cancer has been rising dramatically following economic development and industrialization. Currently, colorectal cancer is the third leading cause of cancer deaths in both males and females in the United States.^1,2

Adenocarcinomas comprise the vast majority (98%) of colon and rectal cancers. Other rare rectal cancers, including carcinoid (0.4%), lymphoma (1.3%), and sarcoma (0.3%), are not discussed in this article. Squamous cell carcinomas may develop in the transition area from the rectum to the anal verge and are considered anal carcinomas. Very rare cases of squamous cell carcinoma of the rectum have been reported.^1,3

Approximately 20% of colon cancers develop in the cecum, another 20% in the rectum, and an additional 10% in the rectosigmoid junction. Approximately 25% of colon cancers develop in the sigmoid colon.¹

The incidence and epidemiology, etiology, pathogenesis, and screening recommendations are common to both colon cancer and rectal cancer. These areas are addressed together.

Pathophysiology

The mucosa in the large intestine regenerates approximately every 6 days. Crypt cells migrate from the base of the crypt to the surface, where they undergo differentiation and maturation, and ultimately lose the ability to replicate.

The significant portions of colorectal carcinomas are adenocarcinomas. The adenoma-carcinoma sequence is well described in the medical literature.^1,4 Colonic adenomas precede adenocarcinomas. Approximately 10% of adenomas will eventually develop into adenocarcinomas. This process may take up to 10 years.¹

Three pathways to colon and rectal carcinoma have been described:

the adenomatous polyposis coli (APC) gene adenoma-carcinoma pathway
the hereditary nonpolyposis colorectal cancer (HNPCC) pathway
ulcerative colitis dysplasia.

The APC adenoma carcinoma pathway involves several genetic mutations, starting with inactivation of the APC gene, which allows unchecked cellular replication at the crypt surface. With the increase in cell division, further mutations occur, resulting in activation of the K-ras oncogene in the early stages and p53 mutations in later stages. These cumulative losses in tumor suppressor gene function prevent apoptosis and prolong the cell's lifespan indefinitely. If the APC mutation is inherited, it will result in familial adenomatous polyposis syndrome.
Histologically, adenomas are classified in three groups: tubular, tubulovillous, and villous adenomas. K-ras mutations and microsatellite instability have been identified in hyperplastic polyps. Therefore, hyperplastic polyps may also have malignant potential in varying degrees.⁵

The other common carcinogenic pathway involves mutation in DNA mismatch repair genes. Many of these mismatched repair genes have been identified, including hMLH1, hMSH2, hPMS1, hPMS2, and hMSH6. Mutation in mismatched repair genes negatively affects the DNA repair. This replication error is found in approximately 90% of HNPCC and 15% of sporadic colon and rectal cancers.^1,6A separate carcinogenic pathway is also described in inflammatory bowel disease (IBD). Chronic inflammation such as in ulcerative colitis can result in genetic alterations which then lead into dysplasia and carcinoma formation.¹

Frequency

United States

Colon and rectal cancer is the third most common cancer in both females and males. The American Cancer Society estimates that 106,100 new cases of colon cancer and 40,870 new cases of rectal cancer will occur in 2009; 75,590 cases of colorectal cancers are expected in men and 71,380, in women.² Approximately 54,090 deaths from colon cancer and 17,290 deaths from rectal cancer are expected to occur in 2009.
Both colon and rectal cancer incidences as well as mortality rates have been decreasing for the last two decades, from 66.3 per 100,000 population in 1985 to 46.4 in 2005.²The rate of decrease accelerated from 1998-2005 (to 2.8% per year in men and 2.2% per year in women), in part because of increased screening, allowing the detection and removal of colorectal polyps before they progress to cancer. The lifetime risk of developing a colorectal malignancy is approximately 6% in the general U.S. population. This decrease is due to a declining incidence and improvements in both early detection and treatment

International

Although the incidence of colon and rectal cancer varies considerably by country, an estimated 944,717 cases were identified worldwide in 2000. High incidences of colon and rectal cancer cases are identified in the US, Canada, Japan, parts of Europe, New Zealand, Israel, and Australia. Low colorectal cancer rates are identified in Algeria and India. The majority of colorectal cancers still occur in industrialized countries. Recent rises in colorectal cancer incidence have been observed in many parts of the Japan, China (Shanghai) and in several Eastern European countries.¹

Mortality/Morbidity

The American Cancer Society estimates that colorectal cancer will account for 9% of all cancer deaths (49,920) in 2009. In the US, mortality rates have been decreasing in both sexes for the past 2 decades. (The 1- and 5-year rate for patients with colon and rectal cancer is 83% and 64%, respectively.) When colorectal cancers are detected early and localized, the 5-year survival rate is 90%.²

Race

The incidence of colorectal cancer tends to be higher in Western nations than in Asian and African countries; however, within the United States, minor differences in incidence exist among whites, African Americans, and Asian Americans. Five-year survival rates are lower among blacks (55%)than whites (66%). Among religious denominations, colorectal cancer occurs more frequently in the Jewish population.²

Sex

The incidence of colorectal malignancy is slightly higher in males than in females. The overall age-standardized incidence of colorectal cancer was 65/100,000 for males and 47/100,000 for females between 1995 and 1999. The male-female ratio is 1.37%. Mortality rates for colorectal cancer were also higher in males (25.4 per 100,000) than in females (18 per 100,000) in 1999. Left colon carcinomas were more likely to be observed in males and right colon carcinomas were more likely to be observed in females.²

Age

The incidence of colorectal cancer starts to increase after age 35 and rises rapidly after age 50, peaking in the seventh decade. More than 90% of colon cancers occur after age 50. However, cases have been reported in young children and adolescents.¹

Clinical

History

All patients should undergo a complete history (including a family history) and assessment of risk factors for the development of rectal cancer. Many rectal cancers produce no symptoms and are discovered during digital or proctoscopic screening examinations.

Bleeding is the most common symptom of rectal cancer, occurring in 60% of patients. Bleeding often is attributed to other causes (eg, hemorrhoids), especially if the patient has a history of other rectal problems. Profuse bleeding and anemia are rare. Bleeding may be accompanied by the passage of mucus, which warrants further investigation.

Change in bowel habits is present in 43% of patients; change is not evident in some cases because the capacity of a rectal reservoir can mask the presence of small lesions. When change does occur it is often in the form of diarrhea, particularly if the tumor has a large villous component. These patients may have hypokalemia, as shown in laboratory studies. Some patients experience a change in the caliber of the stool. Large tumors can cause obstructive symptoms. Tumors located low in the rectum can cause a feeling of incomplete evacuation and tenesmus.

Occult bleeding is detected via a fecal occult blood test (FOBT) in 26% of all cases. Abdominal pain is present in 20% of the cases. Partial large-bowel obstruction may cause colicky abdominal pain and bloating. Back pain is usually a late sign caused by a tumor invading or compressing nerve trunks. Urinary symptoms may also occur if the tumor is invading or compressing the bladder or prostate.

Malaise is a nonspecific symptom and present in 9% of rectal cancer cases. Bowel obstruction due to a high-grade rectal lesion is rare, occurring in 9% of all cases. Pelvic pain is a late symptom, usually indicating nerve trunk involvement, and is present in 5% of all cases. Other manifestations include emergencies such as peritonitis from perforation (3%) or jaundice, which may occur with liver metastases (<1%).

Physical

Physical examination is performed with specific attention to size and location of rectal cancer in addition to possible metastatic lesions, including enlarged lymph nodes or hepatomegaly. The remainder of the colon is also evaluated.

Digital rectal examination (DRE) provides an opportunity to readily detect abnormal lesions. The average finger can reach approximately 8 cm above the dentate line. Rectal tumors can be assessed for size, ulceration, and presence of any pararectal lymph nodes. Fixation of the tumor to surrounding structures (eg, sphincters, prostate, vagina, coccyx and sacrum) also can be assessed. DRE also permits a cursory evaluation of the patient's sphincter function. This information is necessary when determining whether a patient is a candidate for a sphincter-sparing procedure. Rigid proctoscopy is also performed to identify the exact location of the tumor in relation to the sphincter mechanism.

Causes

The etiology of colorectal cancer is unknown, but colorectal cancer appears to be multifactorial in origin and includes environmental factors and a genetic component. Diet may have an etiologic role, especially diet with high fat content.
Approximately 75% of colorectal cancers are sporadic and develop in people with no specific risk factors. The remaining 25% of cases occur in people with significant risk factors--most commonly, a family history or personal history of colorectal cancer or polyps, which are present in 15-20% of all cases. Other significant risk factors are certain genetic predispositions, such as hereditary nonpolyposis colorectal cancer (HNPCC; 4-7% of all cases) and familial adenomatous polyposis (FAP, 1%); and inflammatory bowel disease (IBD; 1% of all cases).
Environmental factors

Diet
A high-fat, low-fiber diet is implicated in the development of colorectal cancer. Specifically, people who ingest a diet high in unsaturated animal fats and highly saturated vegetable oils (eg, corn, safflower) have a higher incidence of colorectal cancer. The mechanism by which these substances are related to the development of colorectal cancer is unknown.

Saturated fats from dairy products do not have the same carcinogenic effect, nor do oils containing oleic acid (eg, olive, coconut, fish oils). Omega-3 monounsaturated fatty acids and omega-6 monounsaturated fatty acids also appear to be less carcinogenic than unsaturated or polyunsaturated fats. In fact, recent epidemiologic data suggest that high fish consumption may provide a protective effect against development of colorectal cancer. Long-term diets high in red meat or processed meats appear to increase the risk of distal colon and rectal cancers.^4,7

The ingestion of a high-fiber diet may be protective against colorectal cancer. Fiber causes the formation of a soft, bulky stool that dilutes carcinogens; it also decreases colonic transit time, allowing less time for harmful substances to contact the mucosa. The decreased incidence of colorectal cancer in Africans is attributed to their high-fiber, low–animal-fat diet. This favorable statistic is reversed when African people adopt a western diet. Meta-analysis of case-controlled studies found that reduction in colorectal cancer risk occurs with increasing intake of dietary fiber.⁴

Increased dietary intake of calcium appears to have a protective effect on colorectal mucosa by binding with bile acids and fatty acids. The resulting calcium salts may have antiproliferative effects, decreasing crypt cell production in the mucosa. A double-blind placebo-controlled study showed a statistically significant reduction in the incidence of metachronous colorectal adenomas.⁸Other dietary components, such as selenium, carotenoids, and vitamins A, C, and E, may have protective effects by scavenging free-oxygen radicals in the colon.

Alcohol
Alcohol intake of more than 30 g daily has been associated with increased risk of developing colorectal carcinoma, with risk of rectal cancer greater than that of colon cancer. Risk appears greater with beer than with wine.⁹Specifically, Kabat et al found that daily beer consumption of 32 ounces or more increases the risk of rectal cancer in men (odds ratio 3.5).¹⁰

Tobacco
Smoking, particularly when started at a young age, increases the risk of colorectal cancer.¹¹Possible mechanisms for tumor development include the production of toxic polycyclic aromatic amines and the induction of angiogenic mechanisms due to tobacco smoke.

Cholecystectomy

Following cholecystectomy, bile acids flow freely, increasing exposure to the degrading action of intestinal bacteria. This constant exposure increases the proportion of carcinogenic bile acid byproducts. A meta-analysis by Giovannucci et al revealed an increased risk of proximal colon carcinoma following cholecystectomy. Although a large number of studies suggest the increased risk of proximal colon cancer in patients following cholecystectomy, the data are not compelling enough to warrant enhanced screening in this patient population.¹

Hereditary factors

The relative risk of developing colorectal cancer is increased in the first-degree relatives of affected patients. For offspring, the relative risk is 2.42 (95% CI: 2.20-2.65); when more than one family member is affected, the relative risk increases to 4.25 (95% CI; 3.01-6.08). If the first-degree family member is younger than 45 years at the time of diagnosis, the risk increase is even higher.¹²

Regarding the personal history of colorectal cancer or polyps: Of patients with colorectal cancer, 30% have synchronous lesions, usually adenomatous polyps. Approximately 40-50% of patients have polyps on a follow-up colonoscopy. Of all patients who have adenomatous polyps discovered via a colonoscopy, 29% of them have additional polyps discovered on a repeat colonoscopy one year later. Malignancy develops in 2-5% of patients. The risk of cancer in people who have had polyps removed is 2.7-7.7 times that of the general population.¹³

Genetic disorders

Familial adenomatous polyposis (FAP)
FAP is an autosomal dominant inherited syndrome that results in the development of more than 100 adenomatous polyps and a variety of extra-intestinal manifestations. The defect is in the APC gene, which is located on chromosome 5 at locus q21. The disease process causes the formation of hundreds of intestinal polyps, osteomas of bone, desmoid tumors, and, occasionally, brain tumors. Individually, these polyps are no more likely to undergo malignant transformation than are polyps in the general population. The increased number of polyps, however, predisposes patients to a greater risk of cancer. If left untreated, colorectal cancer develops in nearly 100% of these patients by age 40. Whenever the hereditary link is documented, approximately 20% of FAP cases are found to be caused by spontaneous mutation.

Hereditary nonpolyposis colorectal cancer
HNPCC is an autosomal dominant inherited syndrome that occurs because of defective mismatch repair genes located on chromosomes 2, 3, and 7. Patients have the same number of polyps as the general population, but their polyps are more likely to become malignant. These patients also have a higher incidence of endometrial, gastric, thyroid, and brain cancers.
The revised Amsterdam criteria are used to select at-risk patients (all criteria must apply):

three or more relatives who are diagnosed with an HNPCC-associated cancer (colorectal, endometrium, small bowel, ureter, or renal pelvis)
one affected person is a first-degree relative of the other two
one or more cases of cancer are diagnosed before age 50
at least two generations are affected
FAP has been excluded
tumors have undergone a pathology review.

Inflammatory bowel disease

The malignant pathway in these patients does not involve any adenoma-carcinoma sequence. Cancer risk increases with duration of disease. After 10 years, the incidence of colorectal cancer in ulcerative colitis (UC) is approximately 1% per year. Patients should be evaluated for dysplastic changes via an annual colonoscopy. Dysplasia is a precursor of cancer and when present, the risk of cancer is 30%.

The incidence of colorectal cancer in patients with Crohn's disease is 4-20 times greater than that of the general population. Cancer occurs in patients with disease of at least 10 years' duration. The average age at cancer diagnosis, 46-55 years, is younger than that of the general population. Cancers often develop in areas of strictures and in de-functionalized segments of intestine. In patients with perianal Crohn's disease, malignancy is often present in fistulous tracts. Patients with Crohn's colitis should undergo the same surveillance regimen as those with UC.

Workup

Laboratory Studies

Routine laboratory studies should include a complete blood count; serum chemistries, including liver and renal function tests; and a carcinoembryonic antigen (CEA) test. A cancer antigen (CA) 19-9 assay, if available, may also be useful to monitor the disease.

Screening CBC may demonstrate a hypochromic, microcytic anemia, suggesting iron deficiency. The combined presence of vitamin B-12 or folate deficiency may result in a normocytic or macrocytic anemia. All men and postmenopausal women with iron deficiency anemia require a GI evaluation.

Liver function tests are usually part of the preoperative workup. The results are often normal, even in patients with metastases to the liver.

Perform a CEA test in all patients with rectal cancer. A baseline level is obtained before surgery and a follow-up level is obtained after surgery. If a previously normalized CEA begins to rise in the postoperative period, this suggests possible recurrence. A CEA level higher than 100 ng/mL usually indicates metastatic disease and warrants a thorough investigation. The steps of the workup are outlined in Figure 1.

Other Tests

Screening for Colon and Rectal Cancer

The process of malignant transformation from adenoma to carcinoma takes several years. The purpose of screening is to eradicate potential cancers while they are still in the benign stage of the adenoma-carcinoma sequence. Screening also increases the likelihood of discovering existing cancers while they are still in the early stage.

Average-risk screening (see Table 1, below): People who are asymptomatic, younger than 50 years, and have no other risk factors are considered at average risk for developing colorectal cancer. Screening of the average-risk population should begin at age 50 years and end at age 75.¹⁴

Guaiac-based Fecal Occult Blood Test (gFOBT)

Perform FOBT yearly by testing 2 samples from each of 3 consecutive stools. If any of the 6 samples is positive, recommend that the patient have the entire colon studied via colonoscopy or flexible sigmoidoscopy. FOBT has significant false-positive and false-negative rates.

Stool DNA Screening (sDNA)

Stool DNA screening is done using polymerase chain reaction of sloughed mucosal cells in stool. This test evaluates for genetic alterations leading to the cancer formation. Compared with no testing, sDNA testing is cost effective and has high sensitivity for invasive cancer.

Fecal Immunochemical Test (FIT)

Fecal immunochemical testing uses a monoclonal antibody assay to identify human hemoglobin. This test is more specific for lower gastrointestinal tract lesions. The presence of the globin molecule is indicative of bleeding in the colon and rectum because the globin molecule is broken down during passage through the upper gastrointestinal tract.

Rigid Proctoscopy

Rigid proctosigmoidoscopy can be performed without an anesthetic, allows direct visualization of the lesion, and provides an estimation of the size of the lesion and degree of obstruction. This procedure is used to obtain biopsies of the lesion, assess ulceration, and determine the degree of fixation. The rigid proctoscopy is proven to be highly reproducible method of determining the level of rectal cancer and it is not dependent on the operator and on the technique. Therefore, it gives an accurate measurement of the distance of the lesion from the anal verge; the latter is critical in deciding which operation is appropriate. The anal verge should be used as preferred landmark, since the lowest edge of the rectal cancer and the anal verge can be visualized simultaneously during rigid proctoscopy evaluation. In conclusion, the level of rectal cancer must be confirmed by rigid proctoscopy.¹⁵

Flexible Sigmoidoscopy (FSIG)

Perform this test every 5 years. Biopsy any lesions identified, and perform a full colonoscopy. With flexible sigmoidoscopy, lesions beyond the reach of the sigmoidoscope may be missed. FSIG introduces significant variability for the level of rectal cancer and level of rectum itself. Therefore FSIG should not be used to determine the level of the rectal cancer.¹⁵

Combined gFOBT and Flexible Sigmoidoscopy

Theoretically, the combination of these 2 tests may overcome the limitations of each test.

Double-Contrast Barium Enema (DCBE)

Although barium enema is the traditional diagnostic test for colonic polyps and cancer, the United States Preventive Services Task Force (USPSTF) did not consider barium enema in its 2008 update of colorectal cancer screening recommendations. The USPSTF noted that barium enema has substantially lower sensitivity than modern test strategies and has not been studied in trials of screening trials, and that its use as a screening test for colorectal cancer is declining.¹⁴

CT Colonography (CTC)
Virtual colonoscopy (CTC) was introduced in 1994. After bowel preparation, the thin-cut axial colonic images are gathered in both prone and supine positions with high-speed helical CT scanner. Then, the images are reconstituted into a 3-dimensional replica of the entire colon and rectum. This provides a good visualization of the entire colon, including the antegrade and retrograde views of the flexures and haustral folds. Since this is a diagnostic study, patients with positive findings should undergo colonoscopic evaluation the same day.

Fiberoptic Flexible Colonoscopy (FFC)

FFC is recommended every 5-10 years. Colonoscopy allows full visualization of the colon and excision and biopsy of any lesions. The likelihood is extremely low that a new lesion could develop and progress to malignancy between examinations.

Table 1: Average Risk Colon and Rectal Cancer Patients Who Should be Screened

Table

Risk Category	Signs and Symptoms
Average risk	No symptoms and age between 50 and 75 years
Average risk	No symptoms requesting screening
Average risk	Change in bowel habits Rectal and anal bleeding Unclear abdominal pain Unclear iron-deficiency anemia
Risk Category	Signs and Symptoms
Average risk	No symptoms and age between 50 and 75 years
Average risk	No symptoms requesting screening
Average risk	Change in bowel habits Rectal and anal bleeding Unclear abdominal pain Unclear iron-deficiency anemia

The US Multi-Society Task Force on Colorectal Cancer (USMSTF) has endorsed a variety of cost-effective screening regimens (http://cme.medscape.com/viewarticle/571201).
Screening options for the detection of adenomatous polyps and cancer for asymptomatic adults 50 years and older include FSIG every 5 years, colonoscopy every 10 years, DCBE every 5 years, or CTC every 5 years (http://cme.medscape.com/viewarticle/571201). Testing options that primarily detect cancer in asymptomatic adults 50 years and older include annual gFOBT with high-test sensitivity for cancer; annual FIT with high-test sensitivity for cancer; or sDNA with high-test sensitivity for cancer, although the optimal interval for sDNA is uncertain. (http://cme.medscape.com/viewarticle/571201)

In summary; each screening test has unique advantages. They have been shown to be cost-effective, and have associated risks and limitations. Ultimately, patient preferences and availability of testing resources guide the selection of screening tests. The main disadvantage of the structural tests is their requirement for bowel preparation. The primary advantage of structural tests is that they can detect polyps as well as cancer. Conscious sedation is usually used for colonoscopy. FSIG is uncomfortable, and screening benefit is limited to sigmoid colon and rectum. Risks for colonoscopy, DCBE, and CTC may rarely include perforation; colonoscopy may also be associated with bleeding. Positive findings on FSIG, DCBE, and CTC usually result in referral for colonoscopy. The advantages of the stool tests are that they are noninvasive, do not require bowel preparation, can be done in the privacy of the patient's home, and are more readily available to patients without adequate insurance coverage or local resources. (http://cme.medscape.com/viewarticle/571201)

In the United States, colon and rectal cancer screening rates have been averaging between 50% and 60%. In a recent study, Brounts and colleagues studied colorectal cancer screening in the Military Healthcare System. In this study, overall screening rates were lower in minority groups than in Caucasians. Also, overall lower screening rates were identified in patients younger than 65 years of age. Although ethnicity-, gender-, and age-related disparities were observed, screening rates were improved in this equal-access health care system when compared with national averages.¹⁶

Screening of high-risk patients (see Table 2, below)

People at increased risk for colorectal cancer include those with affected first-degree relatives, those with a family history of FAP or HNPCC, and those with a personal history of adenomatous polyps, colorectal cancer, or IBD.

First-degree relative affected: Offer family members the same screening tests as the general population; however, begin the screening at age 40 years rather than age 50 years. These people often undergo colonoscopy as their initial screening test, particularly if the relative was diagnosed with cancer at a young age.
Family history of FAP (see Table 2): Genetic counseling and genetic testing are recommended to determine whether the person is a gene carrier. Current tests are approximately 80% accurate. In the remaining 20%, the mutation cannot be identified. Genetic testing is useful only if the test result is positive or if the test is a true negative (ie, mutation present in other family members are not identified in the patient being tested). Flexible sigmoidoscopy should be offered to known gene carriers and persons with an indeterminate carrier status every year to look for polyps. When polyposis develops, consider colectomy.
Family history of HNPCC (see Table 2): Genetic counseling and genetic testing should be offered to individuals whose family histories meet the Amsterdam criteria (see Causes, above). Patients with documented HNPCC should undergo colonoscopy every 1-2 years when 20-40 years of age and every year when older than 40 years. Since these cancers tend to be located on the right side of the colon, flexible sigmoidoscopy is not recommended.
Personal history of adenomatous polyps: Patients who have adenomatous polyps removed during colonoscopy should have a repeat examination at 1 to 3 years. If the findings of this examination are normal, follow up at 5 years.
Personal history of colorectal cancer: Patients who have colorectal cancer and undergo resection for cure should have a repeat colonoscopy after 1 year. If this examination reveals no abnormalities, follow up at 3 years. In the absence of disease, perform colonoscopy every 5 years thereafter.
Personal history of IBD: Surveillance colonoscopy is performed to look for dysplasia as a marker for colorectal cancer in patients with long-standing IBD. These patients should undergo colonoscopy every 1-2 years after 8 years of diffuse disease or after 15 years of localized disease. Random biopsies are performed at specific intervals throughout the colon and rectum. Colectomy is recommended when dysplasia is present.

Table 2: High-Risk Colon and Rectal Cancer Patients Who Should be Included in Surveillance Programs

Table

Risk Category	Signs and Symptoms
High-risk patients due to family history	Family history of colon and rectal cancer First-degree relative with adenoma aged younger than 60 years Genetic family syndromes HNPCC FAP
High-risk patients due to personal history	Personal history of inflammatory bowel disease Personal history of adenomas Personal history of colon and rectal cancer Personal history of genetic family syndromes
Risk Category	Signs and Symptoms
High-risk patients due to family history	Family history of colon and rectal cancer First-degree relative with adenoma aged younger than 60 years Genetic family syndromes HNPCC FAP
High-risk patients due to personal history	Personal history of inflammatory bowel disease Personal history of adenomas Personal history of colon and rectal cancer Personal history of genetic family syndromes

Histologic Findings

Histopathologic features such as poor differentiation, lymphovascular and/or perineural invasion, T4 tumor stage, and clinical findings such as obstruction or perforation, and elevated preoperative CEA levels are all associated with increased recurrence rates and worse survival.¹⁷

Staging

Dukes Classification
In 1932, Cuthbert E. Dukes, a pathologist at St. Mark Hospital in England, introduced a staging system for rectal cancer.
His system divided tumor classification into 3 stages, as follows:

Those limited to the rectal wall (Dukes A)
Those that extended through the rectal wall into extra-rectal tissue (Dukes B)
Those with metastases to regional lymph nodes (Dukes C).

This system was modified by others to include subdivisions of stages B and C, as follows:
Stage B was divided into B1 (ie, tumor penetration into muscularis propria) and B2 (ie, tumor penetration through muscularis propria).
Stage C was divided into C1 (ie, tumor limited to the rectal wall with nodal involvement) and C2 (ie, tumor penetrating through the rectal wall with nodal involvement).
Stage D was added to indicate distant metastases
Tumor, Node, Metastasis (TNM) System
This system was introduced in 1954 by the American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (IUAC). The TNM system is a universal staging system for all solid cancers that is based on clinical and pathologic information. Each category is independent (see Table 3).
Neither the Dukes nor the TNM system includes prognostic information such as histologic grade, vascular or perineural invasion, or tumor DNA ploidy. TNM staging of rectal cancer correlates well with 5-year survival rates of patients with rectal cancer (see the TNM stage-dependent 5-year survival rate for rectal carcinomas).

TNM classification for cancer of the colon and rectum (AJCC)

Primary tumor (T)
TX - Primary tumor cannot be assessed or depth of penetration not specified
T0 - No evidence of primary tumor
Tis - Carcinoma in situ (mucosal); intraepithelial or invasion of the lamina propria
T1 - Tumor invades submucosa
T2 - Tumor invades muscularis propria
T3 - Tumor invades through the muscularis propria into the subserosa or into non-peritonealized pericolic or perirectal tissue
T4 - Tumor directly invades other organs or structures and/or perforates the visceral peritoneum.
Regional lymph nodes (N)
NX - Regional lymph nodes cannot be assessed
N0 - No regional lymph node metastasis
N1 - Metastasis in 1-3 pericolic or perirectal lymph nodes
N2 - Metastasis in 4 or more pericolic or perirectal lymph nodes
N3 - Metastasis in any lymph node along the course of a named vascular trunk
Distant metastasis (M)
MX - Presence of metastasis cannot be assessed
M0 - No distant metastasis
M1 - Distant metastasis
Table 3: Comparison of AJCC Definition of TNM Staging System to Dukes Classification. Five year stage specific survival is also summarized.

Table

Rectal Cancer Stages		TNM Staging	Duke Staging	5-Year Survival
Stage I		T_1-2 N₀ M₀	A	>90%
Stage II	A	T₃ N₀ M₀	B	60%-85%
Stage II	B	T₄ N₀ M₀	B	60%-85%
Stage III	A	T_1-2 N₁ M₀	C	55%-60%
	B	T_3-4 N₁ M₀		35%-42%
	C	T_1-4 N₂ M₀		25%-27%
Stage IV		T_1-4 N_0-2 M₁		5%-7%
Rectal Cancer Stages		TNM Staging	Duke Staging	5-Year Survival
Stage I		T_1-2 N₀ M₀	A	>90%
Stage II	A	T₃ N₀ M₀	B	60%-85%
Stage II	B	T₄ N₀ M₀	B	60%-85%
Stage III	A	T_1-2 N₁ M₀	C	55%-60%
	B	T_3-4 N₁ M₀		35%-42%
	C	T_1-4 N₂ M₀		25%-27%
Stage IV		T_1-4 N_0-2 M₁		5%-7%

The TNM stage – dependent 5-year survival rate for rectal carcinomas is as follows¹⁷:

Stage I: 90%
Stage II: 60% to 85%
Stage III: 27% to 60%
Stage IV: 5% to 7%

Treatment

Medical Care

The surgical definition of the rectum differs from the anatomical definition; surgeons define the rectum as starting at the level of the sacral promontory, while anatomists define the rectum as starting at the level of the 3^rd sacral vertebra. Therefore, the measured length of the rectum varies from 12 cm to 15 cm. The rectum is different than the rest of the colon, in that the outer layer is made of longitudinal muscle. The rectum contains 3 folds, namely valves of Houston. The superior (10 cm to 12 cm) and inferior (4 cm to 7 cm) folds are located on the left side and middle fold (8 cm to 10 cm) is located at the right side.

National Comprehensive Cancer Network guidelines define rectal cancer as cancer located within 12 cm of the anal verge by rigid proctoscopy. This definition was developed by the Dutch Colorectal Cancer Group study, which found that the risk of recurrence of rectal cancer depends on the location of the cancer. Univariate sub-group analyses showed that the treatment effect for surgery alone vs preoperative radiotherapy plus surgery was not significant in patients whose cancer (TNM stage I to IV) was located between 10.1 cm and 15 cm from the anal verge.¹⁸(http://www.medscape.com/viewprogram/8374)

Determination of optimal treatment plan for patients with rectal cancer involves a complex decision-making process. Strong considerations should be given to the intent of surgery, possible functional outcome, and preservation of anal continence and genitourinary functions. The first step involves achievement of cure because the risk of pelvic recurrence is high in patients with rectal cancer and locally recurrent rectal cancer has a poor prognosis. Functional outcome of different treatment modalities involves restoration of bowel function with acceptable anal continence and preservation of genitourinary functions. Preservation of both anal and rectal reservoir function in treatment of rectal cancer is highly preferred by patients. Sphincter-saving procedures for rectal cancer are now considered the standard of care.¹⁹ (Table 3)

Table 3: Factors influencing sphincter and organ preservation in patients with rectal cancer.¹⁹

Table







	ANAL FUNCTION PRESERVATION IN PATIENTS WITH RECTAL CANCER
Factors influencing sphincter preservation		Surgeon training Surgeon volume Neoadjuvant chemoradiotherapy
Factors associated with difficult sphincter preservation		Male sex Morbid obesity Preoperative incontinence Direct involvement of anal sphincter muscles with carcinoma Bulky tumors within 5 cm from the anal verge
Patient selection for Local excision		Lesions located in low rectum (within 8 to 10 cm) Lesions occupying < 1/3 of the rectal circumference Mobile exophytic or polypoid lesions Lesions <3 cm in size T1 lesions Low grade tumor (Well or Moderately differentiated) Negative nodal status (clinical and radiographic)
Disadvantages of APR		Need for permanent colostomy Significantly higher sort-term morbidity and mortality Significantly higher long-term morbidities Higher rate of sexual and urinary dysfunction

Surgical Care

Patient-, tumor-, treatment-, and surgeon-related factors influence the ability to restore intestinal continuity in patients with rectal cancer.
Transanal Excision

The local transanal excision of rectal cancer is reserved for early-stage cancers in a select group of patients. The lesions amenable for local excision are small (< 3 cm in size), occupying less than a third of a circumference of the rectum, preferably exophytic/polypoid, superficial and mobile (T₁ and T₂ lesions), low-grade tumors (well or moderately differentiated) that are located in low in the rectum (within 8 cm of the anal verge) (see Table 3). There should also be no palpable or radiologic evidence of enlarged mesenteric lymph nodes. The likelihood of lymph node involvement in this type of lesion ranges from 0-12%.^19,20(See Table 3.)

Preoperative ERUS should be performed. If nodes are identified as suggestive of cancer, do not perform transanal excision. The lesion is excised with the full thickness of the rectal wall, leaving a 1-cm margin of normal tissue. The defect is usually closed; however, some surgeons leave it open. Unfavorable pathologic features such as positive resection margins, lymphovascular invasion, lymph node metastasis, perineural invasions, and recurrent lesion at follow-up evaluations mandate salvage resection. Usually, an abdominal perineal resection or proctosigmoidectomy with coloanal anastomosis is performed as a salvage resection following failure of local excision.²⁰

The advantages of local excision include rapid recovery, minimal effect on sphincter function, and relatively low perioperative morbidity and mortality. Recovery is usually rapid. The 5-year survival rate after transanal excision ranges from 65-100% (these figures include some patients with T₂ lesions). The local recurrence rate ranges from 0-40%. Patients with lesions that display unfavorable histologic features but are excised completely may be treated with adjuvant radiation therapy.

Cancer recurrence following transanal excision of early rectal cancer has been studied by Weiser et al.²¹Failures due to transanal excision are mostly advanced local disease and are not uniformly salvageable with radical pelvic excision. These patients may require extended pelvic dissection with en bloc resection of adjacent pelvic organs such as the pelvic side wall with autonomic nerves, coccyx, prostate, seminal vesicle, bladder, vagina, ureter, ovary, and uterus. The long-term outcome in patients with recurrent rectal carcinoma who undergo radical resection is less favorable than expected, relative to the early stage of their initial rectal carcinoma.²¹

In summary, the treatment of T₁ and T₂ rectal cancers continues to be challenging. Local excision is associated with higher rate of recurrence, especially in T₂ lesions. Ultimately, 15-20% of patients may experience recurrence. When local recurrence is detected, patients usually have advanced disease, requiring extensive pelvic excisions. Therefore, strict selection criteria are essential when considering local excision. All patients should be informed of the risk of local recurrence and lower cure rates associated with recurrence.^21,19,22(Table 3)

Endocavitary Radiation

This radiotherapy method differs from external-beam radiation therapy in that a larger dose of radiation can be delivered to a smaller area over a shorter period. Selection criteria for this procedure are similar to those for transanal excision (Table 3). The lesion can be as far as 10 cm from the anal verge and no larger than 3 cm. Endocavitary radiation is delivered via a special proctoscope and is performed in an operating room with sedation. The patient can be discharged on the same day.

A total of 6 application of high-dose (20Gy to 30 Gy), low-voltage radiation (50kV) is given over the course of 6 weeks. Each radiotherapy session produces a rapid shrinkage of the rectal cancer lesion. An additional booster dose can be given to the tumor bed. The overall survival rate is 83%, although the local recurrence rate as high as 30%.²⁰
Transanal Endoscopic Microsurgery (TEM)

Transanal endoscopic microsurgery is another form of local excision that uses a special operating proctoscope that distends the rectum with insufflated carbon dioxide and allows the passage of dissecting instruments. This method can be used on lesions located higher in the rectum and even in the distal sigmoid colon. Transanal endoscopic microsurgery has not come into wide use yet because of a significant learning curve and a lack of availability.
Sphincter-Sparing Procedures

Procedures are described that use the traditional open technique. All of these procedures, except the perineal portions, can also be performed using laparoscopic techniques, with excellent results. The nuances of the laparoscopic technique used are beyond the scope of this discussion.

Low anterior resection (LAR):

LAR is generally performed for lesions in the middle and upper third of the rectum and, occasionally, for lesions in the lower third. Because this is a major operation, patients who undergo LAR should be in good health. They should not have any preexisting sphincter problems or evidence of extensive local disease in the pelvis.

Patients will not have a permanent colostomy but should be informed that a temporary colostomy or ileostomy may be necessary. They also must be willing to accept the possibility of slightly less-than-perfect continence after surgery, although this is not usually a major problem.
Other possible disturbances in function include transient urinary dysfunction secondary to weakening of the detrusor muscle. This occurs in 3-15% of patients. Sexual dysfunction is more prominent and includes retrograde ejaculation and impotence. In the past, this has occurred in 5-70% of men, but recent reports indicate that the current incidence is lower.²³

The operation entails full mobilization of the rectum, sigmoid colon, and, usually, the splenic flexure. Mobilization of the rectum requires a technique called total mesorectal excision (TME). TME involves sharp dissection in the avascular plane that is created by the envelope that separates the entire mesorectum from the surrounding structures. This includes the anterior peritoneal reflection and Denonvilliers fascia anteriorly and preserves the inferior hypogastric plexus posteriorly and laterally. TME is performed under direct visualization. Mesorectal spread can occur by direct tumor spread, tumor extension into lymph nodes, or perineural invasion of tumor.^15,23,22

TME yields a lower local recurrence rate (4%) than transanal excision (20%), but it is associated with a higher rate of anastomotic leak (11%). For this reason, TME may not be necessary for lesions in the upper third of the rectum. The distal resection margin varies depending on the site of the lesion. A 2-cm margin distal to the lesion must be achieved. For the tumors of the distal rectum, less than 5 cm from the anal verge, the minimally accepted distal margin is 1 cm in the fresh specimen. Distal intra-mural spread beyond 1 cm occurs rarely (Table 4). Distal spread beyond 1 cm is associated with aggressive tumor behavior or advanced tumor stage.¹⁵

The procedure is performed with the patient in the modified lithotomy position with the buttocks slightly over the edge of the operating table to allow easy access to the rectum.²²(See Table 4) A circular stapling device is used to create the anastomosis. A double-stapled technique is performed. This entails transection of the rectum distal to the tumor from within the abdomen using a linear stapling device. The proximal resection margin is divided with a purse-string device. After sizing the lumen, the detached anvil of the circular stapler is inserted into the proximal margin and secured with the purse-string suture. The circular stapler is inserted carefully into the rectum, and the central shaft is projected through or near the linear staple line. Then, the anvil is engaged with the central shaft, and, after completely closing the circular stapler, the device is fired. Two rings of staples create the anastomosis, and a circularrimordonut of tissue from the proximal and distal margins is removed with the stapling device.

Table 4: Acceptable minimal distal and proximal resectional margins for rectal cancer.¹⁵

Table




Resection Margins	Proximal Resection Margin (cm)	Distal Resection Margin (cm)
Ideal Margins	5 cm or more	2 cm or more
Minimally acceptable margins	5 cm or more	1 cm or more

The anastomotic leak rate with this technique ranges from 3-11% for middle-third and upper-third anastomosis and to 20% for lower-third anastomosis. For this reason, some surgeons choose to protect the lower-third anastomosis by creating a temporary diverting stoma. This is especially important when patients have received preoperative radiation therapy. The rate of stenosis is approximately 5-20%. A hand-sewn anastomosis may be performed; if preferred, the anastomosis is performed as a single-layer technique. The leak and stenosis rates are the same.

In R0 resection, the inferior mesenteric artery (IMA) should be excised at its origin, but this rule is not mandated by available supportive evidence. Patients with non–en-bloc resection, positive radial margins, positive proximal and distal margin, residual lymph node disease, and incomplete preoperative and intra-operative staging would not be considered to have complete resection of cancer (R0 resection).¹⁵Patients with R1 and R2 resection are considered to have an incomplete resection for cure. Incomplete R1 and R2 resection does not change the TNM stage but affects the curability.¹⁵

Colo-anal anastomosis (CAA):

Very distal rectal cancers that are located just above the sphincter occasionally can be resected without the need for a permanent colostomy. The procedure is as already described; however, the pelvic dissection is carried down to below the level of the levator ani muscles from within the abdomen. A straight-tube coloanal anastomosis (CAA) can be performed using the double-stapled technique, or a hand-sewn anastomosis can be performed transanally.²³

The functional results of this procedure have been poor in some patients, who experience increased frequency and urgency of bowel movements, as well as some incontinence to flatus and stool. An alternative to the straight-tube CAA is creation of a colonic J pouch. The pouch is created by folding a loop of colon on itself in the shape of a J. A linear stapling or cutting device is inserted into the apex of the J, and the stapler creates an outer staple line while dividing the inner septum. The J-pouch anal anastomosis can be stapled or hand sewn.

An alternative to doing the entire dissection from within the abdomen is to begin the operation with the patient in the prone jackknife position. The perineal portion of this procedure involves an intersphincteric dissection via the anus up to the level of the levator ani muscles. After the perineal portion is complete, the patient is turned to the modified lithotomy position and the abdominal portion is performed. Either a straight-tube or colonic J-pouch anal anastomosis can be created; however, both must be hand sewn.²³

The advantages of the J pouch include decreased frequency and urgency of bowel movements because of the increased capacity of the pouch. A temporary diverting stoma is performed routinely with any coloanal anastomosis.
Abdominal perineal resection (APR):

APR is performed in patients with lower-third rectal cancers. APR should be performed in patients in whom negative margin resection will result in loss of anal sphincter function. This includes patients with involvement of the sphincters, preexisting significant sphincter dysfunction, or pelvic fixation, and sometimes is a matter of patient preference.

A 2-team approach is often used, with the patient in modified lithotomy position. The abdominal team mobilizes the colon and rectum, transects the colon proximally, and creates an end-sigmoid colostomy. The perineal team begins by closing the anus with a purse-string suture and making a generous elliptical incision. The incision is carried through the fat using electrocautery. The inferior rectal vessels are ligated and the anococcygeal ligament is divided. The dissection plane continues posteriorly, anterior to the coccyx to the level of the levator ani muscles. Then, the surgeon breaks through the muscles and retrieves the specimen that has been placed in the pelvis. The specimen is brought out through the posterior opening, and the anterior dissection is continued carefully. Care must be taken to avoid the prostatic capsule in the male and the vagina in the female (unless posterior vaginectomy was planned). The specimen is removed through the perineum, and the wound is irrigated copiously.Aclosed-suctiondrain is left in place, and the perineal wound is closed in layers, using absorbable sutures. During this time, the abdominal team closes the pelvic peritoneum (this is not mandatory), closes the abdomen, and matures the colostomy.²³

In patients who have rectal cancer with adjacent organ invasion, en bloc resection should be performed in order to not compromise cure. This situation is encountered in 15% of rectal cancer patients. Rectal carcinoma most commonly invades the uterus, adnexa, posterior vaginal wall, and bladder. The urinary bladder is the organ most commonly involved in locally advanced rectal carcinoma. Extended, en bloc resection may involve partial or complete cystectomy.^15,23

Inadequate sampling of lymph nodes may reflect non-oncologic resection or inadequate inspection of pathologic specimens. The use of more extended pelvic lymphadenectomy has been studied for rectal cancer. Extended lymphadenectomy involves removal of all lymph nodes along the internal iliac and common iliac arteries. This procedure has been associated with significantly higher sexual and urinary dysfunction without any additional benefit in local recurrence especially in patients with adjuvant radiotherapy.¹⁷

Treatment of colorectal cancer with liver metastasis:

Chemotherapeutic regimens for liver metastasis including systemic and intrahepatic administration have only had limited benefit. Systemic chemotherapy had 18-28% response rates. It is well accepted that liver resections in selected patients are beneficial. Overall, 5-year survival rates following surgical resection of liver metastasis vary from 20- 40%.

Adjuvant Medical Care

A multidisciplinary approach that includes colorectal surgery, medical oncology, and radiation oncology is required for optimal treatment of patients with rectal cancer. The timing of surgical resection is dependent on the size, location, extent, and grade of the rectal carcinoma. The number of lymph nodes removed (12 or more, minimum: 10) at the time of surgery impacts staging accuracy and prognosis.

Although radical resection of rectum is the mainstay of therapy, surgery alone has a high recurrence rates. The local recurrence rate for rectal cancers treated with surgery alone is 30-50%. Rectal adenocarcinomas are sensitive to ionizing radiation. Radiation therapy can be delivered preoperatively, intraoperatively, or postoperatively and with or without chemotherapy.

Tumor stage, grade, number of lymph node metastasis, lymphovascular involvement, signet cell appearance, achievement of negative radial margins, and distance from the radial margin are important prognostic indicators of local and distant recurrences. Low anterior (LAR) or abdominal-perineal resection (APR) in conjunctions with total mesorectal excision (TME) should be performed for optimal surgical therapy.

Adjuvant radiation therapy:

Preoperative radiation therapy has many potential advantages, including tumor down-staging; an increase in resectability, possibly permitting the use of a sphincter-sparing procedure; and a decrease in tumor viability, which may decrease the risk of local recurrence. Preoperative radiation therapy works better in well-oxygenated tissues prior to surgery. Postoperatively, tissues are relatively hypoxic as a result of surgery and may be more resistant to radiotherapy. If patients have postoperative complications, there may be delay in initiating adjuvant therapy. Preoperative radiation therapy also minimizes the radiation exposure of small bowel loops due to pelvic displacement and adhesions following surgery.^23,24

The disadvantages of preoperative radiation therapy include delay in definitive resection, possible loss of accurate pathologic staging, possible over-treatment of early-stage (stage I and II) rectal cancer, and increased postoperative complications and morbidity and mortality rates secondary to radiation injury. Preoperative radiation therapy decreases the risk of tumor recurrence in patients with stage II or III disease; however, this does not translate into a decrease in distant metastases or an increase in survival rate. Some recent reports cite an increase in survival; however, this is still the minority opinion.

[#preopradiotherapy]In sum, preoperative radiotherapy may be effective in improving local control in localized rectal cancer but is only of marginal benefit in attainment of improved overall survival; it does not diminish the need for permanent colostomies and it may increase the incidence of postoperative surgical infections; it also does not decrease the incidence of long-term effects on rectal and sexual function.²⁵The authors recommend preoperative chemoradiation therapy in patients with large bulky cancers and with obvious nodal involvement.²³

The advantages of postoperative radiation therapy include immediate definitive resection and accurate pathologic staging information before beginning ionizing radiation. The disadvantages of postoperative radiation therapy include possible delay in adjuvant radiation therapy if postoperative complications ensue; no effect on tumor cell spread at the time of surgery; and decreased effect of radiation in tissues with surgically-induced hypoxia. Published randomized trials suggest that preoperative or postoperative radiation therapy appears to have a significant impact on local recurrence but does not increase survival rates.²³

Intraoperative radiation therapy:

Intraoperative radiation therapy is recommended in patients with large, bulky, fixed, unresectable cancers. The direct delivery of high-dose radiotherapy is believed to improve local disease control. Intraoperative radiation therapy requires specialized, expensive operating room equipment, limiting its use.

Adjuvant chemotherapy:

Chemotherapy options for colon and rectal cancer have greatly expanded in recent years, but the efficacy of chemotherapy remains incomplete and its toxicities remain substantial. Combination therapy with use of as many drugs as possible is needed for maximal effect against rectal cancer.

The most useful chemotherapeutic agent for colorectal carcinoma is 5-fluorouracil (5-FU), an antimetabolite. The prodrug, 2-deoxy-5-floxuridine (5-FUDR), is rapidly converted to 5-FU and is used for metastatic liver disease by continuous intrahepatic infusion. Fluorouracil is a fluorinated pyrimidine, which blocks the formation of thymidylic acid and DNA synthesis. Clinically, it offers good radiosensitization without severe side effects, although diarrhea can be dose limiting and, if severe, life-threatening. 5-FU has been used in conjunction with radiation (combined modality) therapy before surgery (neoadjuvant), as well as after surgery.

Stage I (T_1-2, N₀, M₀) rectal cancer patients do not require adjuvant therapy due to their high cure rate with surgical resection. High-risk patients, including those with poorly differentiated tumor histology and those with lymphovascular invasion, should be considered for adjuvant chemotherapy and radiotherapy. The new NCCN guidelines recommend combination therapy with infusional fluorouracil, folinic acid, and oxaliplatin (FOLFOX) as reasonable for patients with high-risk or intermediate-risk stage II disease; however, FOLFOX is not indicated for good- or average-risk stage II rectal cancer.^26,27

Patients with locally advanced rectal cancer (T_3-4, N₀, M₀ or T_any, N_1-2, M₀) should receive primary chemotherapy and radiotherapy. The combination of preoperative radiation therapy and chemotherapy with fluorouracil improves local control, distant spread, and survival. The basis of this improvement is believed to be the activity of fluorouracil as a radiosensitizer. Surgical resection can be done 4 to 10 weeks after completion of chemotherapy and radiotherapy.

Use of FOLFOX or the combination of folinic acid, fluorouracil, and irinotecan (FOLFIRI) is recommended in treatment of patients with stage III or IV disease. (See Table 5.) Cetuximab should not be used in patients with the KRAS mutation.²⁸

Table 5: Colorectal chemotherapeutic regimens

Table











	COLON AND RECTAL CANCER COMMON CHEMOTHERAPY REGIMENS
FOLFOX (every 2 weeks)		Oxaliplatin 85 mg/m² day 1 Leucovorin 200 mg/m² day 1 5-FU 400 mg/m² IV Bolus day 1 and 2 5-FU 600 mg/m² IV Infusion day 1 and 2 (22 hours)
FOLFOX 4 (every 2 weeks) (4 cycles)		Oxaliplatin 85 mg/m² day 1 Leucovorin 200 mg/m² day 1 5-FU 400 mg/m² IV Bolus day 1 and 2 5-FU 2400 mg/m² IV Infusion day 1 (46 hours)
mFOLFOX 6 (Every 2 weeks) (4 cycles)		Oxaliplatin 85 mg/m² day 1 Leucovorin 400 mg/m² day 1 5-FU 400 mg/m² IV Bolus day 1 and 2 5-FU 1200 mg/m² IV Infusion day 2 days
CapeOX (Twice daily x 14 days) (every 3 weeks)		Oxaliplatin 130 mg/m² day 1 Capecitabine 850 mg/m² PO BID for 14 days
FOLFIRI (every 2 weeks)		Irinotecan 165 mg/m² day 1 Leucovorin 200 mg/m² day 1 5-FU 400 mg/m² IV Bolus day 1 and 2 5-FU 600 mg/m² IV Infusion day 1 and 2 (22 hours)
FOLFOXIRI (every 2 weeks)		Irinotecan 180 mg/m² day 1 Oxaliplatin 85 mg/m² day 1 Leucovorin 200 mg/m² day 1 5-FU 3200 mg/m² IV Infusion day (48 hours)
Bevacizumab		5-10 mg/kg IV every 2 weeks with chemotherapy
Cetuximab		400 mg/m² IV day 1, then 250 mg/m² IV weekly

Common adverse effects include rash, fatigue, abdominal pain, nausea, and diarrhea; serious adverse effects include pulmonary fibrosis, severe rash complicated by infections, infusion reactions (for grade I or II reaction, reduce infusion rate by 50%; for grade III or IV reaction, immediately discontinue permanently), ocular toxicity, abdominal pain, vomiting, and constipation; administer using low-protein–binding filter

4Life Transfer Factor

Kamis, 20 Januari 2011

Introduction

Background

Pathophysiology

Frequency

United States

International

Mortality/Morbidity

Race

Sex

Age

Clinical

History

Physical

Causes

Workup

Laboratory Studies

Other Tests

Table

Table

Histologic Findings

Staging

Table

Treatment

Medical Care

Table

Surgical Care

Table

Table

Medication

Antineoplastic agents

Fluorouracil (5-FU, Fluorouracil, Adrucil)

Adult

Pediatric

Pregnancy

Precautions

Vincristine (Vincasar PFS, Oncovin)

Adult

Pediatric

Pregnancy

Precautions

Leucovorin (Wellcovorin)

Adult

Pediatric

Pregnancy

Precautions

Irinotecan (Camptosar, Camptothecin-11, CPT-11)

Adult

Pediatric

Pregnancy

Precautions

Oxaliplatin (Eloxatin)

Adult

Pediatric

Pregnancy

Precautions

Cetuximab (Erbitux)

Adult

Pediatric

Pregnancy

Precautions

Bevacizumab (Avastin)

Adult

Pediatric

Pregnancy

Precautions

Panitumumab (Vectibix)

Adult

Pediatric

Pregnancy

Precautions

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