Genetic testing in families with hereditary nonpolyposis colon cancer

Genetic testing for hereditary nonpolyposis colon cancer (HNPCC) is available, but the rates of acceptance of testing or barriers to participation are not known.

To investigate rates and predictors of utilization of genetic testing for HNPCC.

Cohort study conducted between July 1996 and July 1998.

Hereditary nonpolyposis colon cancer family registry.

Adult male and female members (n = 208) of 4 extended HNPCC families contacted for a baseline telephone interview.

Family education and individual genetic counseling.

Participant acceptance of HNPCC test results.

Of the 208 family members, 90 (43%) received test results and 118 (57%) declined. Of 139 subjects (67%) who completed a baseline telephone interview, 84 (60%) received test results and 55 (40%) declined. Of the 84 subjects who received test results, 35 (42%) received information indicating that they had HNPCC-associated mutations and 49 (58%) that they did not. Test acceptors had higher education levels (odds ratio [OR], 3.74; 95% confidence interval [CI], 2.49-5.61) and were more likely to have participated in a previous genetic linkage study (OR, 4.30; 95% CI, 1.84-10.10). The presence of depression symptoms significantly reduced rates of HNPCC test use (OR, 0.34; 95% CI, 0.17-0.66). Although rates of test use were identical among men and women, the presence of depression symptoms resulted in a 4-fold decrease in test use among women (OR, 0.25; 95% CI, 0.08-0.80) and a smaller, nonsignificant reduction among men (OR, 0.49; 95% CI, 0.19-1.27).

Despite having significantly elevated risks of developing colon cancer, a relatively small proportion of HNPCC family members are likely to use genetic testing. Barriers to test acceptance may include less formal education and the presence of depression symptoms, especially among women. Additional research is needed to generalize these findings to different clinical settings and racially diverse populations.