AUTOSOMAL-DOMINANT INHERITANCE OF EARLY-ONSET BREAST-CANCER - IMPLICATIONS FOR RISK PREDICTION

Background. Improvements in screening techniques have made significant contributions to the early detection of breast cancer. Physicians thu s face the task of providing appropriate screening schedules for their patients. One group for whom this is particularly important are those women with a family history of breast cancer. Methods. In this report , data from the Cancer and Steroid Hormone Study, a population-based, case-control study conducted by the Centers for Disease Control, are u sed to provide age-specific risk estimates of breast cancer for women with a family history of breast cancer. The data set includes 4730 pat ients with histologically confirmed breast cancer age 20-54 years and 4688 control subjects who were frequency matched to patients by geogra phic region and 5-year age intervals. The data set also includes famil y histories of breast cancer in mothers and sisters of both patients a nd control subjects. Results. Genetic models fit previously to these d ata by the authors have provided evidence for a rare autosomal dominan t allele that results in increased susceptibility to breast cancer. In addition, these models predict that women who carry the allele are at greater risk of developing breast cancer at any age than are women wh o do not carry the allele. The increase in risk in carriers versus non carriers does, however, decrease with increasing age. Based on the par ameters of this model, age-specific risks for a woman with one or more relatives affected with breast cancer at various ages at onset are gi ven. Conclusions, These tables can be used for the purpose of counseli ng women at high risk of breast cancer development, that is, women wit h a family history of breast cancer.