Effect of radiation exposure on survival after first solid cancer1 diagnosis
in A-bomb survivors

RERF Life Span Study (LSS)2 analyses have revealed that that atomic bomb radiation effects
differ in excess relative risk (ERR)3 of solid cancer morbidity (incidence of illness) andmortality (death) among A-bomb survivors. A possible explanation is that chromosomal
mutations caused by radiation exposure might heighten cancer’s aggressiveness or weaken
patients’ ability to tolerate cancer treatments, thereby affecting mortality following cancer
diagnosis.
Against that backdrop, this study analyzed radiation effects on survival following cancer
diagnosis, with a focus on whether the subsequent death was caused by the first solid cancer,
other cancer, or non-cancer disease in 20,463 individuals, excluding 2,075 with only deathcertificate records from among the 22,538 people in the LSS study cohort diagnosed with afirst solid cancer during the period 1958–2009.
We found that the effect of radiation exposure before solid cancer diagnosis on mortality
risk from the first solid cancer was not statistically significant — in other words there was
no evidence of radiation effect on mortality in cases of first solid cancer. Nevertheless,deaths from other cancers and noncancer diseases were found to be associated withradiation dose.4 There are potentially multiple reasons for different A-bomb radiation
effects between solid cancer morbidity and mortality in the LSS, but this study suggests thata radiation effect on death from first solid cancer following diagnosis is probably not one ofthese reasons.
Notes
1 Solid cancer:
Refers to cancer that forms a mass in organs or tissues other than hematopoietic cancers suchas stomach cancer, lung cancer, liver cancer, colon cancer, among others. The “first solid cancer”
indicated in the text above refers to the initial appearance of cancer.
2 Life Span Study (LSS):
The main purpose of this study is to investigate the long-term effects of atomic bomb radiationon 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 wereconfirmed to be in Hiroshima and/or Nagasaki at the time of the atomic bombings and about
27,000 who were not in city at the time. This study has tracked over many years about 120,000
subjects.
3 Excess relative risk (ERR):
The increase or decrease of a certain health risk in an exposed group compared with a control
group. An excess relative risk of 0 means that radiation exposure did not affect risk. An excess
relative risk of 1 in the exposed group would indicate a rate of disease that is double the rate in
the unexposed, or control, group.
4 Association between radiation and first solid cancer, other cancer, or non-cancer disease:
The “excess hazard,” a number indicating how much a disease affects rates of survival andmortality, was 0.038 for the first solid cancer but 0.38 for other cancers. Non-cancer diseases
showed an excess hazard of 0.24. The larger this number, the higher the mortality risk. A moredetailed explanation can be found in the paper.
doi. org/10.1016/j.canep.2023.102341

(Doi are permanent, content-specific numbers assigned to most digital information and, in this case,can be 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 further
details about the study, please refer to the full paper published by the journal.