Cancer risk in young women at risk of hereditary nonpolyposis colorectal cancer: implications for gynecologic surveillance.

OBJECTIVES

The lifetime risk of endometrial and ovarian cancers in hereditary nonpolyposis colorectal cancer (HNPCC) is up to 60 and 12%, respectively, in addition to the high risk of colorectal cancer. International guidelines recommend surveillance of those at risk with colonoscopy every 1--2 years from age 20--25 years and annual gynecologic surveillance from 25--35 years for women. We reviewed our own experience to see whether these recommendations were appropriate.

METHODS

Pedigrees of 120 HNPCC families registered with the Familial Bowel Cancer Service at The Royal Melbourne Hospital were reviewed. Ninety families met our criteria for HNPCC and were included in the study. Pedigrees were analyzed to identify early-age onset colorectal and gynecologic cancers and to calculate cumulative incidence of both cancer types for at-risk women (HNPCC-affected and first-degree female relatives of affected family members) for comparison with the general population.

RESULTS

Colorectal cancer occurred in 434 individuals, endometrial cancer in 43, and ovarian cancer in 24. Gynecologic and colorectal cancers were diagnosed at similar ages (mean 49.3 versus 51.8 years; P = 0.25), with 5 (7.1%) gynecologic cancers diagnosed by 35 years. Cumulative incidences of gynecologic and colorectal cancers to ages 25, 30, 35, and 40 years were substantially higher among at-risk women than in the general population.

CONCLUSIONS

Consideration should be given to offering gynecologic cancer surveillance from the age of 25 years, as for colorectal cancer. However, this approach should be individualized as it has yet to be demonstrated that surveillance reduces the mortality of gynecologic cancer in HNPCC.