Validation and use of a mathematical model to estimate the benefits of screening younger women for breast cancer.

A model of breast cancer is validated by showing that predictions from the model are similar to a variety of reported data on breast cancer. In particular, the model reproduces the finding reported from the HIP screening program that there is no statistically significant benefit from screening younger women for breast cancer. Based on the model, it is estimated that yearly screening between age 40 and 70 with a joint modality consisting of a clinical examination and mammography will realize slightly under one-half the gain in life expectancy (from age 40) that would be realized if breast cancer mortality were eliminated. Most of this gain (about 70%) would be realized if only the clinical examination were performed yearly. Up to 90% would be realized if biannual mammograms were added to the yearly clinical examination.