For a woman in her 40s, the risk for breast cancer within the next 5 years can vary substantially, depending on whether she has any risk factors for the disease. Factors that increase the risk for breast cancer include older age, family history of breast cancer, older age at the time of first pregnancy, younger age of first period, history of a breast abnormality that required a biopsy (removal of a sample of breast tissue for laboratory examination), or a history of being exposed to chest radiation (such as in the treatment of another disease). Unfortunately, a mathematical model called the Gail model that predicts the risk for breast cancer among groups is imprecise in predicting an individual woman's risk for the disease.