You Can Reduce Colonoscopy Screening When You’re Older

Two recent reports in JAMA suggest you can probably reduce the frequency of your screening colonoscopies as you get past 80 (or maybe 75 – it depends how long you plan to live). Current guidelines don’t include an upper age cutoff for screening colonoscopy.

First, the risk of developing colorectal cancer following a negative colonoscopy exam changes a little over the years. Provided one excludes those with a positive family history, inflammatory bowel disease (Crohn’s disease, ulcerative colitis), or previous colorectal surgery, the likelihood of colorectal cancer being diagnosed within 6 months of a negative colonoscopy was 70%, within 1 year it was 65%, within 2 years 60%, within 5 years 55%, and within 10 years 30%. (Remember that suspicious polyps are removed at colonoscopy, leading to some degree of ‘protection’.) it can be concluded that the interval of decreased risk after colonoscopy persists for at least 10 years.

Second, the average (mean) extension of life expectancy due to colonoscopy screening was much lower in the over-80 age group (0.13 years, about 1½ months) than in 75-79 year-olds (0.17 years, or 2 months) and in the ‘control’ group of 50-54 year olds (0.85 years = 10 months). Of course these life extension months appear very small, but they are an average, reflecting the results of screening i.e. it includes the benefit of treatment (surgery, radiotherapy and/or chemotherapy) of those individuals identified as having colorectal cancer along with the survival of all those having negative colonoscopy results. Clearly, the benefits of screening are much greater in the younger age group examined, and quite small in the over-80s.

These two studies, together, suggest that a good cutoff for having a screening colonoscopy (unless you’re a special case, as outlined above) is 75. If you have one then you should be getting the ‘benefit’ for 10 years, by which time - age 85 – you’re not going to get getting much benefit from another colonoscopy. This sort of argument will just have to do for the present, until new results are reported.