ARE RELATIVES OF PATIENTS WITH MULTIPLE HNPCC SPECTRUM TUMORS AT INCREASED RISK OF CANCER

Background-Relatives of patients with early onset colorectal cancer, a feature of hereditary non-polyposis colorectal cancer (HNPCC), are at increased risk of colorectal cancer. Aims-To investigate risk in rela tives of patients with multiple primary cancers, another feature of HN PCC. Methods-Details were obtained on patients fi om one region who ha d developed colorectal cancer and a separate primary from the HNPCC tu mour spectrum (colorectal, stomach, urinary, ovary, endometrial). Over all, 157 patients had second primaries occurring between 1990 and 1995 and 128 completed family histories were obtained by structured interv iew (study group). A comparison group of 444 patients with a single co lorectal cancer were similarly interviewed. Results-Fifteen families ( 13%) from the study group were suggestive of HNPCC compared with three (0.7%, p<0.0001) from the comparison group. Overall risk of colorecta l cancer in close relatives of the study group was 3.4 times the gener al population rate compared with 1.8 times for the comparison group. D owel cancer risk was even higher for relatives of bowel/ovary and bowe l/endometrial subgroups, but was similar to the comparison group for t he bowel/bowel subgroup. Finally, extracolonic HNPCC associated cancer s were seen twice as frequently as expected in the general population in relatives of the study group. Conclusion-This study highlights the importance of taking a family history in patients with multiple primar y cancers and indicates the risk of malignancy in their relatives.