Some women inherit a damaged gene that increases their chances of developing the disease.
A woman's family history may put her at risk if her mother, sister, or daughter has or had breast cancer. She also has a strong family history if two or more close relatives, such as aunts or cousins, were diagnosed. A woman's risk of breast cancer may be greater if these close relatives were diagnosed before age 40. What Women Can Do Manage weight. Older women who gained more than 11 pounds since age 18 had a higher risk of breast cancer than women who had gained less than that.