VALIDATION OF FAMILY HISTORY OF BREAST-CANCER AND IDENTIFICATION OF THE BRCA1 AND OTHER SYNDROMES USING A POPULATION-BASED CANCER REGISTRY

A major risk factor for breast cancer is family history of the disease in first-degree relatives. This study evaluates the validity of famil y history information on breast cancer in mothers and sisters of breas t cancer probands from the cancer registry (CR) compared to personal i nterviews (PI) of 359 consecutive population-based cases of breast can cer. Breast cancer is seen in mothers of 14% of probands by CR compare d to 12% by PI. Further, 13% of probands have a sister with breast can cer using CR compared to 12% by PI. Using PI as the standard, the sens itivity of the CR family history data in mothers is 92% and the specif icity is 99%, while in sisters they are 88% and 99%, respectively. The se estimates were calculated on cases where family history information is available in the CR. Sensitivity and specificity are recalculated, recording an ''error'' whenever family history information is not ava ilable, and they are 75% and 68%, respectively, for mothers and 72% an d 70%, respectively, for sisters. Estimates of proband-mother and prob and-sisters familial breast cancer from CR and PI are sufficiently sim ilar to warrant the use of CR family history data in studies of geneti c epidemiology. The family phenotype consistent with the BRCA1 syndrom e was found in four (1.1%) probands, all below age 50 years, while for BRCA 2 there were five (1.4%) probands, three below age 50 years and two 50 years or older. Site-specific familial breast cancer was found in 23 (6.4%) probands. Population-based multiple-case breast cancer fa milies can rapidly be identified through CR. These families can make s ubstantial contributions to the study of genetic and environmental eti ology of the disease as well as benefit from preventive and therapeuti c efforts. As new knowledge and tools in molecular genetics become ava ilable, there is an urgent need for large population-based registries of families at high risk for cancer. (C) 1996 Wiley-Liss, Inc.