Comparison of all solid cancer mortality and incidence doseresponse in the Life Span Study1 of atomic bomb survivors,
1958–2009
In this study, published in 2022, RERF researchers conducted detailed analysis of dose response(rate2 of cancer in relation to radiation dose) for the 1958–2009 period to compare results withprevious analyses of dose response for all solid cancer3 incidence (rate of new cases of cancer)
and all solid cancer mortality (rate of deaths from cancer during a particular period) in the Life
Span Study (LSS) population.
Analyses in the past consistently showed a linear relationship (on a graph, a proportional,straight line) in dose response. Two subsequent RERF papers, one published in 2012 (see:https://www.rerf.or.jp/uploads/2017/08/rr1104-1.pdf)

andonein2017(see:

https://www.rerf.or.jp/library/rr_e/rr1605.pdf ) suggested, in a limited dose range (0–2 gray[Gy]4), an upward response curve for all solid cancer mortality calculated for men and women
combined and for all solid cancer incidence in men. Reasons for the emergence of the non-linear,
curved responses not seen previously were not well understood.
In this new study’s comparative analysis for all solid cancer incidence, a statistically significant
upward curve in dose response was found among men but not among women. For mortality, asomewhat significant upward curve among men and a significant curve among women wereobserved. Other findings on incidence and mortality by follow-up period (1958–1987 or 1988–2009) and age at exposure (0–19 or 20–83 years) suggested that, in the study population aged 0–19 at exposure, there were upward curves for both sexes: among men in both follow-up periods
and among women in the follow-up period of 1988–2009. The current analysis supports evidence
that the upward curve-shaped dose responses observed in the 2012 and 2017 papers are notspecific to men; it was thought to be dependent on the site of cancer occurrence and the age atexposure or time since exposure.
A better understanding of changing dose response patterns is important for radiation protection
standards, and thus further follow-up studies in the future are considered necessary to clarify
the factors and cancer sites related to the curved responses.
Notes
1Life Span Study (LSS):
The main purpose of this study is to investigate the long-term effects of atomic bomb radiation on
the cause of death and cancer incidence. At the time of the 1950 national population census in Japan,
about 94,000 atomic bomb survivors were selected from among those who were confirmed to be in
Hiroshima and/or Nagasaki at the time of the atomic bombings and about 27,000 who were not incity at the time. This study has tracked over many years about 120,000 subjects.

2Rate:Indicates a measure of the frequency with which an adverse event (cancer, specific disease, death,etc.) occurs in a defined study population over a specified period of time.
3
Solid cancer:
Refers to cancer that forms a mass in organs or tissues other than hematopoietic cancers such as
stomach cancer, lung cancer, liver cancer, colon cancer, among others.
4
Gray (Gy):
Gray (1 gray = 1,000 milligray) is a unit of radiation that represents the amount of radiation doseabsorbed by a substance when it is exposed to radiation. The average dose for RERF’s LSS
participants is around 140–200 milligray (0.14–0.2 Gy). As reference, the average annual amount ofradiation we are all exposed to in our daily lives, include medically, is estimated to be around 2–6
milligray (0.002–0.006 Gy).
doi. org/10.1667/RADE-21-00059.1(Doi are permanent, content-specific numbers assigned to most digital information and, in this case, canbe used to link to published abstracts and/or full papers.)

RERF’s objective with this brief outline is to succinctly explain our research for the laypublic. Much of the technical content of the original paper has been omitted. For furtherdetails about the study, please refer to the full paper published by the journal.