请看美国的SEER report的数据

risk that a woman will be diagnosed with breast cancer during the next 10 years, starting at the following ages, is as follows:

• Age 30 . . . . . . 0.44 percent (or 1 in 227)
• Age 40 . . . . . . 1.47 percent (or 1 in 68)
• Age 50 . . . . . . 2.38 percent (or 1 in 42)
• Age 60 . . . . . . 3.56 percent (or 1 in 28)
• Age 70 . . . . . . 3.82 percent (or 1 in 26)

http://www.cancer.gov/cancertopics/factsheet/detection/probability-breast-cancer