The biggest risk factors for breast cancer
are being a woman and growing older.
The average age of diagnosis is 61.
A woman in the United States has a 1 in 8 chance of developing invasive breast cancer during her lifetime, and breast cancer is primarily a disease of older women. It is estimated that a woman age 20 has about a 5 in 10,000 risk of developing breast cancer in the next 10 years; for a woman age 40, it is about 1 in 100, and for a woman age 60, it is about 1 in 28.