Straightening out colonoscopy facts
DEAR DR. ROACH: Could you please advise what the current recommendation is as far as follow-up colonoscopies are concerned?
It has always been my understanding from what I have read that virtually all colon cancers start as polyps in the colon and that it takes between five and 10 years for a polyp to become cancerous.
My doctor says that a colonoscopy every 10 years is sufficient. Do you agree? I’m wondering why so many people I know are having a colonoscopy way more often, with some even having them yearly.
ANSWER: Although there are rare instances where colon cancer begins without polyps, you are right that the vast majority of colon cancers start as polyps (though in certain cases they are harder to see, such as in Lynch syndrome). So development can be prevented by removing polyps that might become cancer.
The optimum interval between colonoscopies depends on what was found on the first colonoscopy.
If everything was completely normal, or if there were only tiny hyperplastic polyps (these are less likely to become cancerous), then a 10-year interval is recommended.
With a small tubular adenoma (at higher risk for developing cancer), a five-year interval is commonly recommended.
Those with larger or higher-risk polyps, such as villous adenomas, a three-year interval is recommended.
For people with genetic syndromes (such as Lynch), annual colonoscopies are recommended after age 40.
I use the guidelines of the American College of Gastroenterology, found at http://tinyurl.com/nolqtym. However, some gastroenterologists recommend more-aggressive screening regimens.
There is a trade-off between the cost (substantial) and risk of harm (small, but not zero) of a colonoscopy and the ability to find more cancers. There is room for individual variation.
DEAR DR. ROACH: My son-inlaw tested positive for the BRCA gene. His maternal grandmother died young from breast cancer, and his aunt is now terminally ill with pancreatic and liver cancers after having breast cancer.
In addition, his mother has had breast cancer, which metastasized to her leg bone. He has already been told that he should be tested yearly for cancer. He is 33 years old.
What are the ramifications for this young man? Furthermore, how does this affect any future children he and my daughter might have?
My daughter feels very strongly that it would be selfish to bring a child into the world. Most often, the BRCA gene is discussed in regard to female carriers.
ANSWER: There are two BRCA genes, BRCA1 and BRCA2. Either increases risk for cancer in those who carry the gene; however, the degree of risk depends on which BRCA gene is involved, the specific mutation involved and the history of cancers in the family.
The gene is present in both men and women: The BRCA1 gene is on Chromosome 17, BRCA2 is on Chromosome 13. These genes are tumor suppressor genes, and losing their function reduces the body’s ability to repair DNA.
Men with BRCA mutations are at increased risk for colon, pancreatic, prostate and male breast cancers. Recommendations for screening for these cancers must be highly individualized.
I am surprised that your son-in-law hasn’t already met with a genetic counselor: It should have been done before he was tested, and certainly afterward, to review his risks in detail.
There is a 50 per cent risk for each child that the gene will be passed on.
Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth @med.cornell.edu.