Cancer Of The Colon And Rectum

Cancer of the Colon and rectum General consideration Colon and rectal account for more cases of cancer in the population of Western countries than any other anatomic site except the skin

Cancer of the colon and rectum is the most frequent cause of death among visceral malignancies that affect both sexes

Cancer of the Colon and rectum General consideration Risk factors include:

* age * a diet rich in fat and cholesterol * inflammatory bowel disease and * genetic predisposition including: hereditary polyposis and nonpolyposis syndromes

Cancer of the Colon and rectum General consideration If detected early, colorectal cancer is curable by surgery

Adjuvant chemotherapy can prolonge survival in disease that has reached the lymph nodes

Radiotherapy is used in cases of rectal cancer to reduce the risk of local recurrence

Cancer of the Colon and rectum General consideration The distribution of cancer of colon and rectum Ascending colon: 22% Transverse colon: 12% Descending colon: 5% Sigmoid colon: 26% Rectum: 35%

Cancer of the Colon and rectum General consideration Pathophysiology The vast majority of colorectal cancers are adenocarcinomas, which arise from preexisting adenomatous polyps that develop in the normal colonic mucosa

Cancer of the Colon and rectum General consideration Pathophysiology Pioneering work by Bert Vogelstein and colleagues over the last 20 years has identified a number of critically important genetic alterations that contribute, through their multiplicity over many years, to the eventual development of colorectal cancer

Cancer of the Colon and rectum General consideration Pathophysiology

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The earliest event appears to involve the APC (adenomatous polyposis coli) gene, which is mutated in individuals affected by familial adenomatous polyposis (FAP) APC mutations are very common in sporadic colorectal cancer, and beta-catenin mutations have also been identified

Cancer of the Colon and rectum General consideration Pathophysiology DNA methylation changes are a relatively early event and have been detected at the polyp stage

Cancer of the Colon and rectum General consideration Pathophysiology ■ Diet The mechanism by which diet contributes to carcinigenesis is under active study

Population with a high incidence of colorectal carcinoma generally consume diets containing more animal protein and fat than populations with a low incidence of this disease

Cancer of the Colon and rectum Frequency International According to the W H O, April 2003 report on global cancer rates: more than 940,000 new cases of colorectal cancer and nearly 500,000 deaths are reported worldwide each year

Cancer of the Colon and rectum Mortality/Morbidity The overall 5-year survival rate from colon cancer is approximately 60%

The 5-year survival rate is different for each stage (Duke’s classification)

Cancer of the Colon and rectum Mortality/Morbidity For Duke’s stage A tumors involving only the mucosa, the 5-year survival rate exceeds 90% Whereas for metastatic colon cancer, the 5-year survival rate is about 5%

Cancer of the Colon and rectum Mortality/Morbidity For Duke’s stage B colon cancers, the 5-year survival rate is greater than 70% And can be greater than 80% if the tumor does not penetrate the muscularis layer

Once the tumor has spread to the lymph nodes (i.e. Duke’s stage C), the 5-year survival rate usually is less than 60%

Cancer of the Colon and rectum Race Recent data demonstrate a decrease in incidence rates of colorectal carcinoma in whites, particularly for the distal colon and rectum Proximal colon carcinoma rates in blacks are considerably higher than in whites

Cancer of the Colon and rectum Sex The frequency of colon cancer is essentially the same among men and women

Age Is a well-known risk factor for colon cancer, and risk begins to rise in people older than 40 years

Cancer of the Colon and rectum Clinical History Approximately 50% of patients present with abdominal pain 35% with ► altered bowel habits 30% with ► occult bleeding and 15% with ► intestinal obstruction

Cancer of the Colon and rectum Clinical History Right-sided colon cancers tend to be larger and more likely to bleed Whereas left-sided tumors tend to be smaller and more likely to be obstructing

Cancer of the Colon and rectum Clinical History Obtain a family history of: colon cancer familial polyposis or ulcerative colitis

Cancer of the Colon and rectum Clinical History Remember: Consider the possibility of cancer of the colon in patients with:

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a fever of unknown origin

► and in patients with polymyositis

Cancer of the Colon and rectum Clinical Physical The physical examination findings may be: (1) completely normal, especially in early stage colorectal cancer (2) or general or specific findings due to progression of the disease may be present

Clinical Physical These may include: weight loss cachexia abdominal discomfort or tenderness liver mass abdominal distention ascites rectal mass rectal bleeding on rectal examination or occult blood by lab test

Cancer of the Colon and rectum Causes A number of risk factors have been associated with colon cancer Colonic polyps (adenomatous) Age Genetic factors

*APC gene mutation *DNA methylation represent a risk for colon cancer development

Cancer of the Colon and rectum Causes Alcohol consumption is a risk factor for gastrointestinal cancer, including colon cancer Diet, and in particular fat content of diet, has been associated with increased risk of colon cancer

Cancer of the Colon and rectum Causes A statistically significant association exists between: Helicobacter exposure and colonic polyps

Tobacco smoking is associated with a higher risk of colon cancer, which appears to be mediated by induction of 5-lipoxygenase–associated angiogenic pathways

Cancer of the Colon and rectum DIFFERENTIALS Crohn Disease Diverticulitis Diverticulosis, Small Intestinal Fecal Incontinence Ileus Inflammatory Bowel Disease Kaposi Sarcoma Peritonitis and Abdominal Sepsis Ulcerative Colitis

Cancer of the Colon and rectum Lab Studies Carcinoembryonic antigen (CEA) Obtaining a preoperative (CEA) level can be helpful in the clinical management of colorectal cancer Example If CEA level is elevated preoperatively, it can be monitored for evidence of recurrence

Lab Studies Carcinoembryonic antigen (CEA) Remember the following 2 things: (1) CEA may be elevated for reasons other than colon cancer, such as: pancreatic or hepatobiliary disease And elevation does not always reflect: cancer or disease recurrence

Lab Studies Carcinoembryonic antigen (CEA) Remember the following 2 things:

(2) Recurrence remains a possibility when CEA is not elevated, even if CEA was elevated preoperatively Findings of other tests, such as: CT scans and colonoscopy must be incorporated in detection of recurrence

Cancer of the Colon and rectum

Lab Studies Other blood lab tests include: standard complete blood cell counts (CBC) and chemistry panels (example, electrolytes, liver test) ► Remember: Liver function testing should be performed, but results can be normal despite the presence of metastatic disease ► Urinalysis

Cancer of the Colon and rectum Imaging Studies Chest radiography: This is part of the routine evaluation and staging workup. It may reveal metastatic spread to the lungs

Cancer of the Colon and rectum Imaging Studies Abdominal/pelvic CT scans Can be useful in diagnosis of colon cancer that has metastasized to: lymph nodes and liver Multiple metastases in the liver render colon cancer incurable by: surgery and chemotherapy

Cancer of the Colon and rectum Imaging Studies Positron emission tomography (PET) imaging may be useful for: ► staging colorectal cancer and ► detecting recurrent disease

TREATMENT Medical Care Systemic chemotherapy 5-Fluorouracil Remains the backbone of chemotherapy regimen for colon cancer, in both: adjuvant and metastatic setting it was established that combination regimens provide improved efficacy and prolonged progression-free survival in patients with metastatic colon cancer

TREATMENT Medical Care Adjuvant (postoperative) chemotherapy The standard therapy for: patients with stage III and some patients with stage II colon cancer, consisted of: fluorouracil in combination with: levamisole and leucovorin

TREATMENT Medical Care Radiation therapy While radiation therapy remains a standard modality for patients with rectal cancer, the role of radiation therapy is limited in colon cancer it is limited to palliative therapy for selected metastatic sites such as: bone or brain metastases

Cancer of the Colon and rectum TREATMENT Surgery (palliative and curative)

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