WASHINGTON – The number of first- and second-degree relatives with colorectal cancer can increase an individual’s risk for CRC, which could require screening to be done more frequently.
“There have been multiple guidelines reported as to what should be done for these individuals,” Harminder Singh, MD, of the University of Manitoba and his associates stated. “However, for the most part, they have not systematically analyzed the data.” He went on to say that, “more importantly, there’s been no recent AGA [American Gastroenterological Association] or Canadian Association of Gastroenterology statement, which led the development of this guideline.”
To address this issue, Dr. Singh and his colleagues conducted a systematic review of 10 literature searches to answer the following five questions concerning colorectal risk and screening practices: What is the effect of a family history of CRC on an individual’s risk of CRC? What is the effect of a family history of adenoma on an individual’s risk of CRC? At what age should CRC screening begin? Which screening tests are optimal? What are the optimal testing intervals for people with a family history of CRC or adenoma?
These questions were developed via an iterative online platform and then further developed and voted on by a team of specialists. GRADE (Grading of Recommendation Assessment, Development and Evaluation) was used to assess the quality of evidence to support these questions.
Similarly, individuals with two or more first-degree relatives with CRC had a two- to fourfold increased risk of developing CRC, compared with the general population. The review also found that, of the 20 recommendation statements from the review panel, there was consensus about 19 of them.
Colorectal cancer screening is recommended for all individuals with a family history of CRC or documented adenoma. Similarly, colonoscopy is recommended as the preferred test for individuals at the highest risk– those with one or more affected first-degree relatives. Fecal immunochemistry tests are considered a viable alternative except in patients with two or more first-degree relatives.
If a patient is considered to have an elevated risk of CRC because of family history, then screening should begin when they are aged 10 years younger than when that first-degree relative was diagnosed, and a 5-year screening interval should be followed after that.
Dr. Singh pointed out that the age of the affected first-degree relative should be considered when weighing an individual’s related risk of developing CRC. For example, having an first-degree relative who is diagnosed after the age of 75 is not likely to elevate an individual’s risk of developing CRC. Individuals with one or more second-degree relatives with CRC or nonadvanced adenoma do not appear to have an elevated risk of developing CRC and should be screened according to average-risk guidelines.
Dr. Singh reported receiving funding for from Merck Canada.
SOURCE: Leddin D. Gastroenterology. 2018 Jun. doi: 10.1016/S0016-5085(18)31083-7.