Solid Cancer Incidence among the Life Span Study of Atomic Bomb Survivors: 1958–2009

Abstract

This is the third analysis of solid cancer incidence among the Life Span Study (LSS) cohort of atomic bomb survivors in Hiroshima and Nagasaki, adding eleven years of follow-up data since the previously reported analysis. For this analysis, several changes and improvements were implemented, including updated dose estimates (DS02R1) and adjustment for smoking. Here, we focus on all solid cancers in aggregate. The eligible cohort included 105,444 subjects who were alive and had no known history of cancer at the start of follow-up. A total of 80,205 subjects had individual dose estimates and 25,239 were not in either city at the time of the bombings. The follow-up period was 1958-2009, providing 3,079,484 person-years of follow-up. Cases were identified by linkage with population-based Hiroshima and Nagasaki Cancer Registries. Poisson regression methods were used to elucidate the nature of the radiation-associated risks per Gy of weighted absorbed colon dose using both excess relative risk (ERR) and excess absolute risk (EAR) models adjusted for smoking. Risk estimates were reported for a person exposed at age 30 years with attained age of 70 years. In this study, 22,538 incident first primary solid cancer cases were identified, of which 992 were associated with radiation exposure. There were 5,918 cases (26%) that occurred in the 11 years (1999-2009) since the previously reported study. For females, the dose response was consistent with linearity with an estimated ERR of 0.64 per Gy (95% CI: 0.52 to 0.77). For males, significant upward curvature over the full dose range as well as restricted dose ranges was observed and therefore, a linear-quadratic model was used, which resulted in an ERR of 0.20 (95% CI: 0.12 to 0.28) at 1 Gy and an ERR of 0.010 (95% CI: -0.0003 to 0.021) at 0.1 Gy. The shape of the ERR dose response was significantly different among males and females (P = 0.02). While there was a significant decrease in the ERR with increasing attained age, this decrease was more rapid in males compared to females. The lowest dose range that showed a statistically significant dose response using the sex-averaged, linear ERR model was 0-100 mGy (P = 0.038). In conclusion, this analysis demonstrates that solid cancer risks remain elevated more than 60 years after exposure. Sex-averaged upward curvature was observed in the dose response independent of adjustment for smoking. Findings from the current analysis regarding the dose-response shape were not fully consistent with those previously reported, raising unresolved questions. At this time, uncertainties in the shape of the dose response preclude definitive conclusions to confidently guide radiation protection policies. Upcoming results from a series of analyses focusing on the radiation risks for specific organs or organ families, as well as continued follow-up are needed to fully understand the nature of radiation-related cancer risk and its public health significance. Data and analysis scripts are available for download at: http://www.rerf.or.jp .

Lung, Laryngeal and Other Respiratory Cancer Incidence among Japanese Atomic Bomb Survivors: An Updated Analysis from 1958 through 2009

“…Follow-up began on January 1, 1958 and continued until the earlier of first primary cancer diagnosis, death or December 31, 2009. Additional details about the cohort have been given elsewhere (4, 5). …”

“…Because individual residence history data were not available for all cohort members, city-, sex-, age- and time-dependent residence probabilities estimated from the Adult Health Study (AHS) clinical contact data were used to compute migration-adjusted person years (5). …”

“…They also reported a super-multiplicative interaction for cohort members who smoked approximately 10 cigarettes per day, but little radiation-related risk in heavy smokers. Following the report of most recently updated cancer incidence data in the LSS (5), the analyses in the current study make use of ten additional years of follow-up (through 2009), revised smoking data, improved radiation dose estimates and updated migration information for cohort participants. Here, we evaluate the relationship between radiation exposure and lung cancer risk, paying special attention to the nature of the joint effect of radiation and smoking.…”

Overview of Biological, Epidemiological, and Clinical Evidence of Radiation Hormesis

“…There are many published data on the cohort [67,68,69,70,71]. A nearly linear relationship exists between cancer incidence and the radiation dose in the high-dose range.…”

Late Effects of Radiation from Conception to Adolescence: Risk in Intrauterine Irradiation, Hereditary Effects, Solid Tumours

“…Atom bombalarından 60 yıldan fazla zaman geçmesine rağmen, sağ kalanlar arasında gözlenen solid tümörler belgelere dayanan majör sağlık problemi olmaya devam etmektedir (22). Yaşam boyu çalışması (Life Span Study) ve benzerlerinden elde edilen epidemiyolojik çalışmaların sonuçları ve Birleşmiş Milletler Atomik Radyasyon Bilimsel Komitesi, çocukların radyasyona; lösemi, tiroid, deri, beyin ve meme kanserlerini içine alan kanser tiplerinin %25'i için yetişkinlerden daha duyarlı olduğunu belirtmektedir.…”