THE INCIDENCE OF BREAST-CANCER FOLLOWING MANTLE FIELD RADIATION-THERAPY AS A FUNCTION OF DOSE AND TECHNIQUE

Background: There is an increased incidence of breast cancer following mantle field radiation therapy for Hodgkin's disease (HD), We reviewe d the experience at the Mallinckrodt Institute of Radiology (MIR) for radiation factors related to the development of breast cancer after ma ntle field radiation therapy for HD. Methods: The radiation therapy re cords of 152 women treated with mantle field irradiation for HD at MIR between 1966-1985 were reviewed for the development of breast cancer and treatment-related factors, All patients had a minimum of 5 years o f follow-up, The treatment era (1966-1974 vs, 1975-1985), stage of HD, mediastinal dose, axillary dose, maximum dose from the anterior field (anterior d(max) dose), the anterior-posterior:posterior-anterior (AP :PA) ratio, age at the time of treatment, length of follow-up, and his tory of splenectomy were analyzed as possible contributing factors for the development of breast cancer, The observed number of breast cance rs was compared to the expected number based on age-adjusted incidence s from the Connecticut Tumor Registry. Results: Ten breast cancers occ urred in the population, Eight involved an upper outer quadrant, In a multivariate analysis, the development of breast cancer was significan tly associated with axillary dose, Patients in the early treatment era were at an increased risk for the development of breast cancer due to high anterior d(max) and breast doses from weighting the fields anter iorly on a low energy linear accelerator, The use of current radiation therapy techniques was not related to an increased risk of breast can cer with a median follow-up of 13 years. Conclusions: A high dose to t he axilla and the anterior d(max) point is significantly associated wi th the development of breast cancer after mantle field irradiation for HD, Efforts to protect the breast from high doses will likely lessen the increased risk of breast cancer in women treated with radiation th erapy for HD. (C) 1997 Elsevier Science Inc.