Bulletin: Colon Cancer Detection and Testing (includes Rectal Cancer)
The exact causes of colorectal cancer are not known. However, studies have shown that certain factors are linked to an increased chance of developing this disease including polyps. Polyps are abnormal growths that protrude from the inner wall of the colon or rectum. They are relatively common in people over age 50. Most polyps are benign (noncancerous), but experts believe that the majority of colorectal cancers develop in polyps known as adenomas. Detecting and removing these growths may help prevent colorectal cancer. The procedure to remove polyps is called a polypectomy.
What tests should I have?
Screening is checking for health problems before they cause symptoms and further injury. Colon cancer screening can detect cancer; polyps; nonpolypoid lesions, which are flat or slightly depressed areas of abnormal cell growth; and other conditions. If screening reveals a possible problem, diagnosis and treatment should occur promptly. In addition, finding and removing polyps or other areas of abnormal cell growth may be one of the most effective ways to prevent colorectal cancer development. Also, colorectal cancer is generally more treatable when it is found early, before it has had a chance to spread.
Your doctor should do one or more of these screening tests:
Fecal occult blood test (FOBT)—This test checks for hidden blood in fecal material (stool). Currently, two types of FOBT are available. One type, called guaiac FOBT, uses the chemical guaiac to detect blood in samples of stool. Usually, samples of stool from three different bowel movements are collected for this test.
The other type of FOBT is called immunochemical or immunohistochemical FOBT. This test detects blood in the stool using special antibodies. Depending on the type of immunochemical FOBT, stool samples from one to three bowel movements are collected. Studies have shown that FOBT, when performed every 1 to 2 years in people ages 50 to 80, can help reduce the number of deaths due to colorectal cancer by 15 to 33 percent.
Sigmoidoscopy—In this test, the rectum and lower colon are examined using a lighted instrument called a sigmoidoscope. During this test, precancerous and cancerous growths in the rectum and lower colon can be found and either removed or biopsied for further testing. Studies suggest that regular screening with sigmoidoscopy after age 50 can help reduce the number of deaths from colorectal cancer.
Colonoscopy —In this test, the rectum and entire colon are examined using a lighted instrument called a colonoscope. During colonoscopy, precancerous and cancerous growths throughout the colon can be found and either removed or biopsied, including growths in the upper part of the colon, where they would be missed by sigmoidoscopy.
Virtual colonoscopy (also called computerized tomographic colonography)—In this test, special x-ray equipment is used to produce pictures of the colon and rectum. A computer then assembles these pictures into detailed images that can show polyps and other abnormalities. Because it is less invasive than standard colonoscopy and sedation is not needed, virtual colonoscopy may cause less discomfort and take less time to perform.
Double contrast barium enema (DCBE)—In this test, a series of x-rays of the entire colon and rectum are taken after the patient is given an enema with a barium solution and air is introduced into the colon. The barium and air help to outline the colon and rectum on the x- rays. Research shows that DCBE may miss small polyps. It detects about 30 to 50 percent of the cancers that can be found with standard colonoscopy.
Routine digital rectal exam (DRE) -- Doctors perform this test during routine checkups and may use this exam to check for abnormalities in the lower rectum. As part of the routine exam, they may also perform a single-specimen guaiac FOBT on stool collected during a DRE, but research has shown that this approach is not very accurate and cannot be recommended as the only method of screening for colorectal cancer.
Of course, there are specific criteria, advantages and disadvantages, including potential harms, of each test.
We at Berger & Lagnese will investigate whether your doctors properly and timely tested you and then followed up on your test results.