Every woman is at risk for breast cancer.
By studying large numbers of women all over the world, researchers have found certain risk factors that increase a woman's chance of getting the disease. The risk of breast cancer increases as a woman gets older. This disease is uncommon in women under age 35. The risk of getting breast cancer increases for a woman whose mother, sister or daughter has had the disease. The woman's risk further increases if her relative's cancer developed before menopause or if it affected both breasts.