A woman aged 50 stands a 2.38 percent, or one in 42, chance of developing breast cancer within the next 10 years, according to the National Cancer Institute. Age is the strongest risk factor for breast cancer, followed by a family history of breast cancer.
Other risk factors that increase a woman's chance of developing breast cancer include inherited changes in certain genes, such as BRCA1 and BRCA2, having dense breast tissue that is more difficult to read in a mammogram, and starting menstruation before age 12 or starting menopause after age 55, explains the National Cancer Institute. Women who have a first full-term pregnancy after age 30 or who have never been pregnant have increased risk of breast cancer as well. Radiation treatment to the chest or breasts, particularly before age 50, also increases a woman's lifetime risk. Lifestyle factors linked to an increased risk of breast cancer include obesity after menopause and alcohol use.
As of February 2015, a woman born in the United States has about a one in eight, or a 12.4 percent, lifetime risk of developing breast cancer, explains the National Cancer Institute. To decrease breast cancer risk, women can remain physically active and maintain an appropriate weight, particularly after menopause.