Cancers of the colon, rectum, appendix and some anal cancers are collectively referred to as colorectal cancer, which is the second leading cause of cancer death in the United States. Colorectal cancer strikes both men and women, with 130,000 new cases diagnosed and approximately 56,000 deaths from colorectal cancer in the U.S. each year. According to the Harvard Center for Cancer Prevention, over half of all colon cancer deaths in the U.S. could be prevented by regular screening, combined with a healthy lifestyle.
Because colorectal cancer is a highly curable disease when detected early, the best form of prevention is screening and early detection. Colon cancer often begins as an adenomatous polyp, which is a precancerous lesion that takes 10 to 15 years to transform into cancer. There are several screening programs used to detect early stage colorectal cancer and polyps. Currently available screening strategies include the fecal occult blood test (FOBT), flexible sigmoidoscopy, colonoscopy and double contrast barium enema.
Screening and Risk Factors
The American Cancer Society currently recommends that patients at average risk for colorectal cancer begin screening at the age of 50 with an annual 3-sample fecal occult blood test (FOBT) and/or a flexible sigmoidoscopy every 5 years. It is also recommended that a colonoscopy be performed every 10 years, and if a FOBT is positive, or if adenomas are found during the sigmoidoscopy. Some physicians recommend that a double-contrast barium enema be performed every 5 to 10 years after age 50, however, current research indicates that the colonoscopy may be a more effective screening procedure.
It is recommended that individuals with an increased risk for developing colorectal cancer begin screening at a younger age and continue with frequent evaluations to detect polyps or cancer when they are most treatable. Individuals with a personal or family history of adenomatous polyps, familial adenomatous polyposis (FAP), hereditary nonpolyposis colorectal cancer (HNPCC) or colorectal cancer should talk to their doctor about the most appropriate screening procedure and schedule. Individuals interested in colorectal cancer screening should discuss the options with their physician in order to determine the most appropriate screening procedure.
Fecal Occult-Blood Test (FOBT): When colon cancers begin, they are typically associated with minor bleeding that is not easily visible. The fecal occult-blood test checks for hidden blood in the stool by having patients check their own stool for hidden “occult” blood with a special kit. Recently, results from an 18-year study indicated that annual or biannual FOBT can significantly reduce the incidence of colorectal cancer. When the test indicates the presence of blood, additional tests, such as colonoscopy, are necessary.
Flexible Sigmoidoscopy: During this procedure, a physician uses a lighted tube to look inside the rectum and the lower part of the colon (sigmoid colon) for polyps or areas suspicious for cancer. The physician may perform a biopsy in order to collect samples of suspicious tissues or cells for closer examination. A flexible sigmoidoscopy is typically an outpatient procedure that does not require sedation, anesthesia or pain medication. There are minimal complications associated with this procedure.
Colonoscopy: During this procedure, a longer flexible tube that is attached to a camera is inserted through the rectum, allowing physicians to examine the internal lining of the colon for polyps or other abnormalities. The physician may perform a biopsy in order to collect samples of suspicious tissues or cells for closer examination. This is a more difficult procedure than sigmoidoscopy, often requiring sedation. Significant complications occur in 1% of patients or less.
Double-Contrast Barium Enema: A chalky substance called barium is inserted through the rectum and into the colon and rectum. The patient then undergoes x-rays of the colon and rectum so that the physician can evaluate the area for polyps or other abnormalities. The barium helps open the colon so that the x-rays are more detailed and clear. Due to the low sensitivity for the detection of large polyps, there is a decreased interest in this approach.
Identifying High Risk Patients
While these screening strategies help to monitor for the development of adenomatous polyps and colorectal cancer, other tests exist which may help identify patients who are at higher risk for the development of colorectal cancer.
Predictive Genetic Testing: Patients with hereditary non-polyposis colorectal cancer (HNPCC) account for 3-5% of all colorectal cancer. In addition, individuals with the HNPCC gene mutations have an 80% lifetime risk of developing colorectal cancer. A predictive medicine test for hereditary colorectal cancer is now available. This test detects disease-causing mutations in two genes, MLH1 and MSH2, which are responsible for the majority of hereditary non-polyposis colorectal cancer (HNPCC). This test may allow patients who are identified to be at a high risk for HNPCC to have earlier and more frequent exams and to have pre-cancerous polyps removed. Individuals interested in genetic testing should consult with their physicians about the risks and benefits of this procedure.
Research is ongoing to develop and refine the optimal screening programs for individuals at risk of developing colorectal cancer. Although screening for colorectal cancer can save lives, less than 30% of appropriate persons have undergone screening for colorectal cancer in comparison to over 70% of appropriate women who have been screened for cervical and breast cancer. Researchers hope that a growing awareness and more patient-friendly screening techniques will increase the number of people undergoing screening for colorectal cancer. For more information about risk factors and screening for colorectal cancer, talk to your doctor.
Information presented in The Daily Tip is offered as a guide to augment a patient’s research of cancer and treatment and does not replace the advice of a doctor. For more information on a specific cancer, go to CancerConsultants.com, www.cancer.gov, and consult your physician. For more information on colorectal cancer, patients can visit the Web sites of the Colon Cancer Alliance and the Colorectal Cancer Network.
Tags: Colon Cancer