BreastCa is a breast cancer risk prediction tool. In particular, it is designed to be a fast, easy-to-use, and accurate implementation of two commonly-used models of breast cancer risk prediction: the Gail and Claus models.The most commonly used model for breast cancer prediction was originally developed by Gail et al. in 1989 (model 1) using data on women participating in the Breast Cancer Detection and Demonstration Project (BCDDP).The other commonly-used model was developed by Claus et al. on the basis of data from the Cancer and Steroid Hormone Study (CASH), and concentrates solely on family history risk factors.