Other factors that increase breast cancer risk are family history (particularly breast cancer in the mother or sister); a genetic mutation known as the BRCA gene (most common in those of Eastern European Jewish descent) greatly increases the risk of breast cancer, particularly when combined with a family history of the disease.

Being overweight or obese or eating a diet high in saturated fat puts a woman at greater risk of breast cancer. Exercising regularly lowers the risk of breast cancer.

Because hormones, particularly estrogen, fuel breast cancer growth, women who got their periods early or didn't start menopause until later in life are at greater risk, as are women who didn't have children or had their first child late in life. Taking hormone therapy (HRT) for menopause symptoms also increases breast cancer risk.

Smoking cigarettes or drinking more than one alcoholic drink a day increases breast cancer risk.