Do I Really Need a Colonoscopy?
Colorectal Cancer strikes 140,000 people in the United States, and kills 49,000 yearly despite our ability to prevent 80 to 90% of colon cancers with colonoscopy. 90% of people with colon cancer have no family history of this cancer, so that is not much of a comfort for the many people who do not have family members with cancer. Almost all of the people with early cancer and precancerous growths such as polyps feel entirely well, without any bowel symptoms related to the tumor growing in the lining of the large intestine or colon. Colonoscopy can prevent colorectal cancer by removing these precancerous colon polyps.
“So if family history is not a guide, and symptoms are not a guide, how do I know if I am at risk?”
- Adult men and women over the age of 50 are at increased risk of developing cancer of the colon and rectum, the second leading malignancy in the United States.
- People of African descent should begin screening for colon cancer earlier, at age 45 years (American College of Gastroenterology Guideline) or 40 (American College of Physicians Guideline).
- Smoking, even for former smokers, is associated with one third more colon cancers and 2-3 times as many at risk polyps.
- Obesity in the abdomen is associated with 2-3 times more risk for colon cancer.
“How often do I need colonoscopy?”
The standard guidelines of the American College of Gastroenterology are to have colonoscopy screening every 10 years. This guideline is based on balancing prevention with containing costs to society. I treat individuals, and feel that these guidelines fail to consider that studies of both colonoscopy and CT scan colonography missed 10% of large growths over 1cm. These larger growths are clearly one of the reasons for some patients presenting with colon cancer within 3 to 5 years after colonoscopy.
Colonoscopy every 10 years clearly saves lives, but no test is perfect. My recommendations, are colonoscopy every 5 years beginning at age 50, and beginning at age 45 for African Americans. The national guidelines clearly recommend that colonoscopy should be every ten years as this is more cost-effective.
“My father had colon cancer. What can I do to prevent cancer and not have to go through the surgery and chemotherapy he needed?”
People who have colon cancer before the age of 60 may have a gene mutation that may be inherited by their family members. Screening should begin at age 40 in their children and siblings and every 3 years.
“What if I have colon polyps?”
Colon polyps are growths in the lining of the large intestine and rectum. They come in different flavors and are not all the same. In the rectum and lower sigmoid colon relatively flat small growths are frequently seen known as hyperplastic polyps. Sometimes there can be many of these hyperplastic polyps. They are overgrowths, but not tumors. Not all polyps are tumors. The hyperplastic polyps of the left colon and rectum are not a risk for colon cancer development.
The majority of the polyps we are concerned about are benign tumors called adenomas. Adenomas have a cancerous tendency called dysplasia. Dysplasia is the precancerous tendency that is analogous to the dysplasia a gynecologist would find on an abnormal pap smear of the cervix. The large majority of adenomas have low grade dysplasia. Although this is a predisposition to cancer, referring to all adenomas as precancerous is a bit of a stretch.
The adenomas or benign tumors that have a higher predilection for cancer risk are:
- Adenomas with high grade dysplasia. These have sometimes been referred to as carcinoma in situ, because they have all the characteristics of cancer except that the growth has not yet invaded into the deeper layers of the bowel.
- Large adenomas over 1centimeter in size.
- Multiple (3 or over) adenomas even if small.
- Villous adenomas which are a more feathery flat carpet-like growth
- Serrated polyps. These are often relatively flat, on the right side of the colon, can be confused with hyperplastic polyps, and can often be missed due to their flat nature.
These at risk polyps must be completely removed. If it is not clear that the polyp is completely removed, a close follow up is needed, within a month to a year depending on the biopsy result.. Some benign polyps that are not able to be removed with the colonoscope will need surgery to prevent a benign tumor from becoming cancer. Follow-up colonoscopy after complete removal would be in1 to 3 years depending on clinical circumstances.
“My brother has colon polyps. Am I at greater risk of getting colon cancer?”
Here the risk depends on whether the polyp is an adenoma, and whether the family member is under 60. Again not all people with colon polyps have adenomas. Development of adenomas at age under 60 should lead to family members having colonoscopy beginning at age 40, at least every five years.
“I can wait until I am 50 before having a colonoscopy”
For Caucasian people without family history or symptoms, we recommend colonoscopy beginning at age 50. There are exceptions to this. African-Americans and Afro-Caribbean people should begin colonoscopy at age 45 according to the American College of Gastroenterology and American Society of Gastrointestinal Endoscopy. The American College of Physicians recommends beginning at age 40.
If you have symptoms such as rectal bleeding, or changes in your bowel movements from your usual, then age is not a factor in investigating the cause of these symptoms. Rectal symptoms may be due to a variety of causes, such as hemorrhoids, anal fissures, ulcerative colitis and proctitis, an infection, or even colorectal cancer. Many people have had colon cancer before age 40 including Katie Couric’s husband, Jay Moynihan, and baseball great Daryl Strawberry.
“Both my mother and her mother had colon cancer. When should I start having colonoscopy, and how often?”
Lynch Syndrome, a genetic condition causing colon cancer may be due to a defect in the DNA mutation mismatch repair genes. In addition to colon cancer, there is a predisposition to endometrial, stomach, ovarian, pancreas, and less commonly cancers of the renal pelvis (kidney), biliary tract, and brain tumors; sebaceous gland adenomas and keratoacanthomas; and carcinoma of the small bowel. The development of colon cancer before the age of 60 should be considered for this mutation by looking for microsatellite instability on the biopsy specimens of the cancer. The mutation mismatch repair genes can be tested in the patient with cancer under 50 years of age or any age with two of the Lynch Syndrome cancers.
Family members should be tested for a genetic condition in the following circumstances:
- Colon cancer or any of the above Lynch Syndrome cancers occurs before the age of 50 in a first degree family member (parent, brother, sister)
- Two Lynch syndrome cancers occurring at any age in first or second degree family members
Listen Now as Dr. Carol A. Burke, MD, FACG discusses Colorectal Risk Factors including Family History and Lynch Syndrome with a patient who has Familial Colon Cancer. From the American College of Gastroenterology.