Soft tissue sarcomas in atomic-bomb survivors of Hiroshima and Nagasaki

Abstract

Lower levels of ionizing radiation may be associated with the risk of radiation-induced soft tissue sarcomas. A linear dose-response model noted an ERR= 0.98 per Gy for soft tissue sarcomas. High levels of ionizing radiation have been associated with a risk of radiation-induced soft tissue sarcomas following therapeutic or occupational exposures. However, it remains relatively unknown whether the development of such lesions are associated with lower levels of radiation exposure. This study was a longitudinal, cohort-based analysis of the development of soft tissue sarcomas in 80,181 atomic bomb survivors of Hiroshima and Nagasaki followed from 1958 to 2001. Utilizing colon dose in Gray (Gy), the excess relative risk (ERR) per Gy of ionizing radiation absorbed dose was assessed. Various subject demographics, age-specificity, and survival parameters were also assessed. The study identified 105 soft tissue sarcomas (36 males, 69 females). The mean ages at the time of the bombings and diagnosis were 27.0 and 63.6 years, respectively. The mean colon dose was 18 cGy. The uterus and stomach were the most common organ-specific sites of sarcoma development. Leiomyosarcomas (35.2%) and malignant fibrous histiocytomas (10.5%) were the most prevalent sarcomas. An overall unadjusted 5-year survival rate of 42% was noted. A linear dose-response model fit the data well with an ERR of 0.98 per Gy (95% CI: 0.11-2.39; p=0.02). In contrast to the reported literature, this study is the first to suggest that lower levels of ionizing radiation may be associated with a risk of radiation-induced soft tissue sarcomas. A linear dose-response model produced an ERR of 0.98 per Gy for soft tissue sarcomas.