1 to 2-year colonoscopy intervals reduce the risk of colorectal cancer in families with Lynch syndrome

The present study evaluated the risk of developing colorectal cancer (CRC) in Lynch syndrome carriers who were followed by colonoscopies at 1 to 2-year intervals.

Lynch syndrome is an inherited condition that predisposes patients to cancer of the large intestine (CRC). Lynch syndrome can also cause cancers of the uterine muscle (endometrial cancer), ovaries, stomach and other organs. The disease is caused by a defective gene (mutation) that can be inherited in an autosomal dominant pattern. This means that if one patient carries the mutation, there is a 50% chance that mutation will be passed on to each child. However, relatives of Lynch syndrome patients can be carefully monitored through surveillance colonoscopies in order to prevent CRC. A colonoscopy is a procedure doctors use to look inside the large intestine using a thin flexible tube with a camera called a colonoscope. Until 1995 the recommended interval for colonoscopy was 2 to 3 years but it was then reduced to 1 to 2 years. 

The study included 205 Lynch syndrome families with a total of 745 affected members (the Lynch syndrome group) and 46 families with CRC who tested negative for Lynch syndrome, with 344 affected members (the non-Lynch group). All families with Lynch syndrome and non-Lynch were offered colonoscopy surveillance for CRC at 1 to 2-year intervals. After about 7 years of follow up and with a surveillance interval of approximately 16 months, 33 patients (4.4%) from the Lynch syndrome group developed CRC, of which 83% were confined to the large intestine. Taken together, the overall calculated risk of developing CRC at 10 years in Lynch syndrome carriers was 6%. In contrast, only 6 (1.7%) patients from the non-Lynch group developed a CRC during the follow-up period. 

In summary, as expected the study found a significantly higher risk of developing CRC (under regular surveillance) in Lynch syndrome families compared to non-Lynch families. However, through surveillance CRC was caught in an early stage, thus improving patients’ chances for long-term survival. 

Despite these findings, colonoscopy is an unpleasant procedure, with risks involved. Therefore, frequent colonoscopies may be difficult to manage for some patients. Since the risk of developing advanced CRC during colonoscopy surveillance for Lynch syndrome patients is low at a short surveillance interval (16 months), colonoscopies can be recommended at larger intervals (maximum 3 years). Therefore patients can be spared of a frequent painful and unpleasant procedure and they may adhere more to the surveillance program.