THE RISK OF ENDOMETRIAL CANCER IN HEREDITARY NONPOLYPOSIS COLORECTAL-CANCER

PURPOSE: Hereditary nonpolyposis colorectal cancer (HNPCC) is characte rized by increased risk for cancer, especially colorectal cancer. It h as been recommended that colon cancer control programs for family memb ers be expanded to include endometrial cancer, the commonest extracolo nic cancer observed in HNPCC families. We estimated the age-specific a nd cumulative endometrial cancer risk for women at high risk for HNPCC . PATIENTS AND METHODS: Family history data from three large HNPCC reg istries were combined for this study. High risk family members were id entified without regard to extracolonic cancer. Life table methods wer e used to calculate estimates of risk. RESULTS: One thousand eighteen women from 86 families were included in the study. Cumulative incidenc e was 20% by age 70, compared to 3% in the general population. Risk wa s highest in women most likely to carry the HNPCC gene (P <0.001). In this group, during the highest risk years (age 40 to 60), average annu al risk exceeded 1%. There was no significant difference among the reg istries, despite different ascertainment practices regarding endometri al cancer. CONCLUSION: Interventions to reduce endometrial cancer morb idity and mortality are justified by the risk levels observed. Prophyl actic total hysterectomy and bilateral salpingo-oophorectomy should be recommended to women in HNPCC families who have a syndrome cancer or offspring with a syndrome cancer. Endometrial cancer screening should be available to women at high risk. Studies of screening protocols are needed.