Recent Topics: Screening for Colon Cancer
Frank S. Pancotto, M.D., FACP
Introduction
Cancer of the Colon and Rectum, colorectal cancer (CRC), is a common and potentially fatal disease. Approximately one-third of individuals who develop colon cancer die from it. The good news is - it is preventable. The average person has approximately a 5% lifetime risk of developing colon cancer. 90% of these occur in persons over 50 years old. Black Americans have a higher risk of dying from colon cancer that do white Americans. American Indians and Hispanics have a lower risk. Cigarette smoking, diets high in fat and red meat both increase risk. Calcium supplements, folic acid supplements and non-steroidal anti-inflammatory drugs such as aspirin, ibuprofen and naproxen all decrease risk.
Why Screen?
Most colon cancers begin as small tumors (polyps) which grow over time. Some of these develop precancerous changes and eventually become cancerous, spread beyond the colon and become fatal. The time course from a beginning polyp to the development of cancer takes approximately 10 years. Since it takes so long for the development of colon cancer, there are ample opportunities for the detection of cancers at the polyp stage and removing them before they become cancerous. Regular screening and removal of polyps reduces the risk of colon cancer by over 90%. Early detection of a cancerous polyp allows for removal and cure of the cancer before it has an opportunity to spread.
Who to Screen?
There are factors that increase the risk for the development of colon cancer:
Family history
If a family member, especially a first degree relative (parent, brother, sister or child) has colon cancer, the average risk (5%) is doubled. Several family members with colon cancer increase the risk even more. If the family member had colon cancer before age 55, the risk to remaining family members is increased further.
Prior colon polyps or colon cancer
Individuals who have a history of colon polyps or cancer have an increased risk and should be surveyed on a regular basis.
Inflammatory bowel disease
The risk for colon cancer is increased in those with ulcerative colitis or Crohn’s disease of the colon. Patients with irritable bowel syndrome do not have an increased risk.
Screening Tests
Five tests are currently available for colon cancer screening. Fecal occult blood test, sigmoidoscopy, barium enema, colonoscopy and CT colonoscopy or Virtual colonoscopy.
Fecal occult blood test
Colon cancers and polyps sometimes bleed into the digestive tract in minute amounts that are not detected with the naked eye. Chemical tests on the stool can pick this up and allow for further evaluation, usually with a colonoscopy.
Sigmoidoscopy
This allows for direct viewing with a camera the lower one-third of the colon. If a polyp is found then the patient is usually referred for colonoscopy.
Barium enema
This is an x-ray examination of the colon, preceded by instilling a mixture of air and barium through the rectum. If an abnormality is found then the patient is usually referred for colonoscopy.
Colonoscopy
This examination allows for direct viewing of the entire colon with a camera and, if a polyp is found, it can be removed at the same time. Preparation for the examination requires a thorough cleaning of the colon. Preparation that is suboptimal means that the examination of the colon will also be suboptimal. A sedative is generally given for the examination. There is a chance for bleeding when removing a polyp or for a tear to occur in the colon wall that may require surgery to repair. Chances for bleeding depend on the size of the polyp and are less than 1 in 100 for large polyps and much smaller for smaller polyps. Risks for causing a tear are less than 1 in 1,000.
Virtual Colonoscopy
This is the newest examination of the colon and may not be available in all locations or covered by all insurance plans. For this examination the patient is prepared as for a colonoscopy, then air is placed into the rectum and the patient scanned with an ultra fast CT scanner. The scan allows for a 3D construction of the colon that can later be examined by a Radiologist. The procedure is safer than colonoscopy but does not allow for polyp removal at the same setting. The patient would then need to be referred for a colonoscopy with polyp removal.
Which Test for Whom?
It is generally recommend that every American, once they reach age 50, should begin regular colon cancer screening. In years past, fecal occult blood testing and sigmoidoscopy were the standard techniques used. Today, most would recommend a colonoscopy beginning at age 50 with repeat exams every 10 years or sooner if a polyp is found or the patient is at increased risk for colon cancer. Virtual Colonoscopy is being tested and applied in a variety of different settings. It is the procedure of choice in patients who cannot undergo a colonoscopy or in whom the colonoscopy was incomplete.
Dr. Frank S. Pancotto is a board certified gastroenterologist at Cabarrus Gastroenterology Associates, LLP in Concord, NC. Cabarrus GI provides high quality, personalized care to patients in Cabarrus and surrounding counties. Thomas T. Long, M.D., Frank S. Pancotto, M.D., David F. Rhodes, M.D., Thomas A. Dalton, M.D., Robert T. Foust, M.D., and Mark D. Aldous, M.D. are available for appointments Monday-Thursday, 8:30 a.m. to 4:30 p.m. and Friday 8:30 a.m. to 3:00 p.m. Call 704-783-1840 for further information.
