The epidemiology of endometrial cancer in hereditary nonpolyposis colorectal cancer.

Family members from hereditary nonpolyposis colorectal cancer (HNPCC) families are at an increased risk of developing endometrial cancer. The present study was performed to investigate the epidemiology of endometrial cancer associated with HNPCC. Data on 125 cases of endometrial cancer from HNPCC families were collected from seven countries. The mean age at diagnosis was 48 years (range: 27-72 years). Fifty-seven percent of the cases were diagnosed under 50 years of age and 98 percent under 65 years. The mean ages at diagnosis of endometrial cancer were not significantly different between the countries. At the time of the investigation, 58 of the 125 cases had died (mean age at death: 59 years; range: 32-88 years). Fifteen of the 125 (12%) patients died from endometrial cancer. In 75 of the 113 (61%) endometrial cancer cases, a second primary cancer occurred. Most of these cancers (54 out of 75) were colorectal cancers. In 18 (15%) of the cases of endometrial cancers, more than two primary cancers occurred. In conclusion, endometrial cancer in HNPCC develops at a significant earlier age than in the general population. More than half of the cases had a second primary tumor. Endometrial cancer is an infrequent cause of death in the HNPCC families. A prospective study is warranted to assess the value of surveillance for endometrial cancer in these families.