All human beings are exposed to the influence of ionizing radiation from natural, medical and other artificial sources. Therefore, the influence of radiation as a risk factor for
cancer development has been among the most studied external factors over the last 6 decades, particularly with respect to radiosensitive tissues and organs. It has been known that female breast tissue is highly sensitive to the carcinogenic effects of radiation, particularly when exposure takes place at younger age. All women are exposed to low doses of radiation for several common reasons (kind of occupation, medical diagnostic procedures, residence background radiation) whose effects on
breast cancer development cannot be documented, and thus it is believed that ionizing radiation is not primary or major risk factor leading to development of
breast cancer. Radiobiological studies revealed a specific event caused by radiation through recognition of the critical target in radiation-induced
carcinogenesis. Accordingly, mutagenic and carcinogenic effects of ionizing radiation are evidenced both in vitro and in vivo, although the incidence of
radiation-induced cancers is low. The highest risk of radiation- induced
breast cancer is evidenced in the sub-population of female patients who have undergone
radiotherapy for either malignant or non-malignant diseases, including benign
breast diseases in their childhood or young age. Therefore, as a means of prevention in this group of population, indications for application of ionizing radiation, both diagnostic and therapeutic, should be highly selective, meaning that radiation should be applied only if the possible benefit outweighs the risk.