Background & aims: A family history (FH) of colorectal cancer (CRC) increases the risk of developing CRC. These consensus recommendations developed by the Canadian Association of Gastroenterology and endorsed by the American Gastroenterological Association, aim to provide guidance on screening these high-risk individuals.
Methods: Multiple parallel systematic review streams, informed by 10 literature searches, assembled evidence on 5 principal questions around the effect of an FH of CRC or adenomas on the risk of CRC, the age to initiate screening, and the optimal tests and testing intervals. The GRADE (Grading of Recommendation Assessment, Development and Evaluation) approach was used to develop the recommendations.
Results: Based on the evidence, the Consensus Group was able to strongly recommend CRC screening for all individuals with an FH of CRC or documented adenoma. However, because most of the evidence was very-low quality, the majority of the remaining statements were conditional ("we suggest"). Colonoscopy is suggested (recommended in individuals with ≥2 first-degree relatives [FDRs]), with fecal immunochemical test as an alternative. The elevated risk associated with an FH of ≥1 FDRs with CRC or documented advanced adenoma suggests initiating screening at a younger age (eg, 40-50 years or 10 years younger than age of diagnosis of FDR). In addition, a shorter interval of every 5 years between screening tests was suggested for individuals with ≥2 FDRs, and every 5-10 years for those with FH of 1 FDR with CRC or documented advanced adenoma compared to average-risk individuals. Choosing screening parameters for an individual patient should consider the age of the affected FDR and local resources. It is suggested that individuals with an FH of ≥1 second-degree relatives only, or of nonadvanced adenoma or polyp of unknown histology, be screened according to average-risk guidelines.
Conclusions: The increased risk of CRC associated with an FH of CRC or advanced adenoma warrants more intense screening for CRC. Well-designed prospective studies are needed in order to make definitive evidence-based recommendations about the age to commence screening and appropriate interval between screening tests.