Further analysis of incidence of multiple myeloma among
atomic bomb survivors, 1950-1994
Concerning any relationship between radiation and multiple myeloma1, epidemiologicalstudies carried out until this point, including RERF’s Life Span Study (LSS)2, have notyielded consistent and clear results. In this analysis, cases of multiple myeloma observed in
the LSS between 1950 and 1994 were examined with a particular focus placed on diagnostic
accuracy.
Among 122 multiple myeloma cases identified during the defined period, 67 (55%) wereconsidered confirmed, 23 (19%) probable, and 32 (26%) uncertain, in terms of diagnostic
accuracy. The occurrence (incidence) of confirmed cases increased with increasing age andwas highest in the 70-and-older age-group. Statistical analysis indicated that, per 1 gray(Gy)4 of radiation, excess relative risk (ERR)3 (i.e., likelihood that multiple myeloma
resulted from radiation exposure) was 0.44. Although not a statistically clear association
between radiation and multiple myeloma incidence, that number was higher than the ERRof 0.02 previously reported by RERF.
In the aforementioned analysis time-period, most A-bomb survivors younger than 20 at thetime of bombing had not yet reached the age (in their 70s) at which multiple myeloma is
more likely to occur. Therefore, continued long-term observation with carefulconsideration of diagnostic accuracy is necessary to fully understand the risk of multiple
myeloma due to radiation exposure.
Notes
1
Multiple myeloma: This form of myeloma occurs when abnormal plasma cells (a type ofwhite blood cell) concentrate in the bone marrow and become cancerous (when normal
cells turn into cancer cells), forming tumors in bones throughout the body.
2Life Span Study (LSS): The main purpose of this study is to investigate the long-term effects
of atomic bomb radiation on cause of death and cancer incidence. At the time of the 1950
national population census in Japan, about 94,000 atomic bomb survivors were selectedfrom 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 in city at the time. This study has
tracked over a span of many years about 120,000 members.
3
Excess relative risk (ERR): Excess relative risk is the increase or decrease of a certain healthrisk in an exposed group compared with a control group. An excess relative risk of 0 meansthat radiation exposure did not affect risk. An excess relative risk of 1 in the exposed groupindicates a rate of disease that is double the rate in the unexposed, or control, group.
4
Gray (Gy): Gray (1 gray = 1,000 milligray) is a unit of radiation that represents the amountof radiation dose absorbed 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 of radiation we are all exposed to in our daily lives, including
medically, is estimated to be around 2–6 milligray (0.002–0.006 Gy).
doi. org/10.1182/bloodadvances.2022009154(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 lay public.
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.