Surveillance Outcomes in Patients With a Family History of Colorectal Cancer in Both Parents

A family history of colorectal cancer (CRC) in a first-degree relative is a well-established risk factor for CRC. When individuals have 2 parents with CRC, the impact on risk is uncertain, and there are no established guidelines for surveillance. We sought to define the surveillance practices and outcomes in individuals with a family history of CRC in both parents.

We identified probands with a family history of CRC in both parents from our Hereditary Gastrointestinal Cancer Database. Charts were retrospectively reviewed for colonoscopy surveillance patterns and incidence of adenomas and CRC.

Sixty-six patients met the inclusion criteria. Forty-two patients (64%) had genetic testing, and no pathogenic germline mutations were identified. During a mean surveillance period of 144 ± 82.2 months and a mean surveillance interval of 33.4 ± 16.6 months, a total of 3.2 ± 8.9 adenomas were found per patient. These were small (median 6.5 mm), and 96% exhibited only low-grade dysplasia. Six patients (9%) were diagnosed with CRC at a mean age of 61.5 ± 11.3 years, corresponding to an incidence rate of 14 cases/10,000 person-years. Patients with CRC were older at first colonoscopy than those without cancer (59 vs 46 years, P = .03), and half of these cases were diagnosed at this first colonoscopy.

Among patients with a family history of CRC in both parents, cases of CRC were seen primarily in those who significantly delayed their first colonoscopy. Initiation of colonoscopy at age 40 should be recommended to individuals with CRC in both parents, consistent with recommendations for those with 1 first-degree relative with CRC.