BREAST-CANCER AFTER RADIOTHERAPY FOR SKIN HEMANGIOMA IN INFANCY

Between 1920 and 1959, 9675 women were irradiated in infancy for skin hemangioma at Radiumhemmet, Stockholm. They were exposed to low to mod erate doses of ionizing radiation. The mean age at first exposure was 6 months and the mean absorbed dose to the breast anlage was 0.39 Gy ( range <0.01-35.8 Gy). The breast cancer incidence was analyzed by reco rd linkage with the Swedish Cancer Register for the period 1958-1986. Seventy-five breast cancers were found [standardized incidence ratio = 1.24; 95% confidence interval (CI) 0.98-1.54] after a mean absorbed d ose of 1.5 Gy in the breasts with cancer, The analyses showed a signif icant dose-response relationship with a linear model estimate for the excess relative risk (ERR) of 0.38 at 1 Gy (95% CI 0.09-0.85). This re lationship was not modified significantly by age at exposure or by dos e to the ovaries. The ERR increased significantly with time after expo sure and for greater than or equal to 50 years after exposure the ERR at 1 Gy was 2.25 (95% CI 0.59-5.62). The fitted excess absolute risk ( EAR) was 22.9 per 10(4) breast-year gray. The breast absorbed dose and time after exposure were important risk determinants for breast cance r excess risk. Forty to 50 years of follow-up was necessary for the ex cess risk to be expressed. The study confirms previous findings that t he breast anlage of female infants is sensitive to ionizing radiation. (C) 1996 by Radiation Research Society