Genetics: Hereditary colorectal cancer

Sean M. Blaine; Carol Cremin; Judith Allanson; Heather Dorman; Clare A. Gibbons; Christina Honeywell; Wendy S. Meschino; Joanne Permaul; June C. Carroll

One in 16 Canadians will develop colorectal cancer (CRC). Increasing age is the main risk factor—fewer than 10% of CRC cases are hereditary. However, hereditary nonpolyposis colorectal cancer (HNPCC) can cause up to an 80% lifetime risk of CRC and substantially increases the risk of endometrial, ovarian, and stomach cancers.

Bottom line

Individuals with “high risk” family histories of colorectal, endometrial, and other HNPCC-related cancers should be offered referral for genetics services. Increased surveillance by annual colonoscopy, beginning at 20 to 25 years of age, is an effective preventive measure for individuals with HNPCC gene mutations. Individuals at moderate risk of CRC should be offered colonoscopic screening beginning 10 years earlier than the youngest age of CRC diagnosis in a family member or no later than age 40.

The complete Gene Messenger—Hereditary Colorectal Cancer by the GenetiKit research team is available on CFPlus.* Past Gene Messenger articles can be accessed on-line at www.cfp.ca. On the home page, click on Collections in the left-hand menu, then click on Genetics.

Acknowledgment

Funding was provided by the Canadian Institutes of Health Research.

Footnotes

Competing interests

None declared
The GenetiKit research team, a group of family physicians, genetic counselors and geneticists, designed the Gene Messenger series to provide practical information to help family physicians and their patients make informed choices about rapidly emerging genetic discoveries. The series is a collection of up-to-date, definitive, short reviews on genetics topics that have made headlines, and offers recommendations regarding referral for genetic services or testing.
↵* The Gene Messenger on hereditary colorectal cancer is available at www.cfp.ca. Go to the full text of this article on-line, then click on CFPlus in the menu at the top right-hand side of the page.