30 years follow-up and increased risks of breast cancer and leukaemia after long-term low-dose-rate radiation exposure
Menée à Taïwan auprès de 6 242 personnes ayant été exposées depuis 1982, sur leur lieu de résidence ou dans des bâtiments scolaires, à de l'acier contaminé au colbalt 60, cette étude évalue l'association entre une exposition sur le long terme à des radiations du colbalt 60 et le risque de cancer, notamment de cancer du sein ou de leucémie (durée de suivi : 30 ans)
Background: The current study followed-up site-specific cancer risks in an unique cohort with 30 years’ follow-up after long-term low-dose-rate radiation exposure in Taiwan. Methods: 6242 Taiwanese people received extra exposure in residential and school buildings constructed with Co-60-contaminated steel from 1982 until informed and relocated in early 1990s. The additional doses received have been estimated. During 1983–2012, 300 cancer cases were identified through the national cancer registry in Taiwan, 247 cases with minimum latent periods from initial exposure. The hazard ratios (HR) of site-specific cancers were estimated with additional cumulative exposure estimated individually. Results: Dose-dependent risks were statistically significantly increased for leukaemia excluding chronic lymphocytic leukaemia (HR100mSv 1.18; 90% CI 1.04–1.28), breast cancers (HR100mSv 1.11; 90% CI 1.05–1.20), and all cancers (HR100mSv 1.05; 90% CI 1.0–1.08, P=0.04). Women with an initial age of exposure lower than 20 were shown with dose response increase in breast cancers risks (HR100mSv 1.38; 90% CI 1.14–1.60; P=0.0008). Conclusions: Radiation exposure before age 20 was associated with a significantly increased risk of breast cancer at much lower radiation exposure than observed previously.