Exposure to large amounts of radiation early in life—such as atomic bomb explosions in Japan and therapeutic radiation for certain cancers—has been linked to an increased risk of breast cancer [37-43]. For example, women treated with radiation therapy for Hodgkin's disease at a young age have about three to seven times the risk of developing breast cancer compared to women with Hodgkin's disease who were never treated with radiation therapy [36-38,41,42]. Although radiation therapy increases the risk of breast cancer later in life, its benefits in the treatment of Hodgkin's disease or other cancers outweigh this risk.
The amount of radiation exposure and age at the time at the exposure play important roles in determining breast cancer risk later in life. In general, the higher the amount of radiation a person is exposed to and the younger the age at exposure, the greater the risk. For example, the risk of developing breast cancer from therapeutic radiation exposure is very high for a woman exposed before the age of 20 but is very small if she is exposed after the age of 40.
Mammography and X-rays
Very low doses of radiation—such as from X-rays—do not have a large impact, if any, on breast cancer risk. While the radiation exposure during mammography can increase the risk of breast cancer, this increase in risk is very slight. Any potential risks of screening tests like mammography are thought to be strongly outweighed by their benefits. Studies show that the benefits of mammography outweigh the risks for women aged 40-50. For women aged 50 and older, these benefits are far greater [41-46].
To learn more about mammography, click here.
Updated 08/14/08
