Patients with Hodgkin's disease who had been treated with radiation therapy is shown to have higher incidence of breast cancer during the later year of life. Best evidence for the increased risk of breast cancer with radiation comes from survivors of atomic bomb explosions in Japan. They have been shown to have significant increase in the incidence of breast cancer compared to unexposed
persons. This increased incidence appears to occur about 15 to 20 years after exposure to radiation. Younger the age at which the woman gets exposure to radiation, higher is the risk of development of breast cancer. Radiation associated with routine X-rays and mammograms not shown to be associated with increased risk of breast cancer.