 Family history

If you have a mother, sister or daughter with breast or ovarian cancer or both, or a male relative with breast cancer, you have a greater chance of also developing breast cancer. In general, the more relatives you have who were diagnosed with breast cancer before reaching menopause, the higher your own risk. If you have one first-degree relative — a mother, sister or daughter — who was diagnosed with the disease before age 50, your risk is doubled. If you have two or more relatives, your risk increases even more. Just because you have a family history of breast cancer doesn't mean it's hereditary, though. Most people with a family history of breast cancer (familial breast cancer risk) haven't inherited a defective gene, such as BRCA1 or BRCA2. Rather, cancer becomes so common in women who live into their 80s and beyond that random, noninherited breast tumors may appear in more than one member of a single family.