BRCA1 and breast cancer: Some models are based solely on family history, such as the Claus model [7], some are based on family history, BRCA1/2 carrier status, and polygenes such as the BOADICEA model [5], whereas others incorporate nongenetic risk factors, such as the BCRAT model [3,8-10] and the International Breast Cancer Intervention Study model (IBIS, also called the Tyrer Cuzick model) [6].