Reference material for June 27, 2007 press release

Title of paper: Solid Cancer Incidence in Atomic Bomb Survivors: 1958–1998
Radiation Research 168, July 2007 issue (Refer to Note 1)

Background and objective of researchWith the aim of studying health effects of A-bomb radiation, the Radiation Effects
Research Foundation (RERF) has conducted a mortality follow-up since 1950 of about
120,000 members of the Life Span Study (LSS) cohort. RERF has also engaged in cancer
incidence studies since 1958, based on use of local cancer registries in Hiroshima andNagasaki.
Comprehensive analyses of radiation effects on solid cancer incidence in the LSS cohort
were recently completed, leading to publication of the paper in question. The paper reports
on analyses conducted from a new perspective, with use of the new dosimetry system DS02
and after extension of the study period 11 years from the previous 1994 report.
Methods
The analyses were based on 17,448 first primary solid cancers diagnosed from 1958
through 1998 among a total of 105,427 cohort members with individual DS02 dose estimates
who were alive and not known to have had cancer prior to 1958. Radiation-associated risks
were assessed for all solid cancers as a group, for 19 specific cancer sites and for five histology
groups. (Refer to Note 2.) The magnitude of radiation-associated risks was investigated,along with the shape of dose response, how the risks vary with gender and age at exposure, andhow such risks differ between cancer sites.
Results1)

Results in principle confirming the 1994 report
It was estimated that about 850 (about 11%) of the cases among the LSS cohort
members with colon dose of 0.005 Gy or greater were associated with atomic bombradiation exposure.
ii) It was shown that the dose-response curve within the 0–2-Gy range was linear.
iii) It was estimated that, at attained age of 70 years after exposure at age 30, solid cancer
rates increased by about 35% per Gy for men, 58% per women, and 47% for bothgenders.
iv) For all solid cancers as a group, excess relative risk decreased by about 17% per decade
increase in age at exposure. Excess absolute risk appeared to increase throughout thestudy period. (Refer to Note 3.)v) Significant radiation-associated increase in cancer risk was seen for such sites as oralcavity, stomach, colon, liver, lung, skin, breast, ovary, bladder, nervous system andthyroid. There was no indication of a statistically significant increase in risk forcancers of the rectum, gallbladder, pancreas, prostate, or kidney. (See Slides 1, 2, and3.)i)

2)

New findingsi) Statistically significant dose response within the 0–0.15-Gy range was also observed.
ii) Risk of esophagus cancer was found to be significant.
iii) It was suggested that radiation exposure at ages less than 20 years might increase riskof uterine corpus cancer.
iv) Observation by histological type of cancer suggested increase in risk for all histologicaltypes considered, including sarcoma.

Note 1:The paper is available on the homepage of Radiation Research, a U.S. scientific journal on
health effects of radiation. (URL: http://www.rrjournal.org)
Note 2: Histological types of cancers
Analyses were conducted by classifying tumors into five subgroups on the basis of the tissue
from which the malignant neoplasm originated: epithelial carcinoma (1. squamous cellcarcinoma, 2. adenocarcinoma, and 3. other epithelial malignancies) and non-epithelial
carcinoma (4. sarcoma, and 5. other non-epithelial cancers).
Note 3: Risk index
Excess relative risk: rate (mainly indicated by percentage) of risk increase per unit dose
Excess absolute risk: absolute value of increased incidence per unit dose

Dose-Response Curve of All Solid Cancers(LSS, Incidence Study, DS02, 1958-1998)

Longitudinal Change in Risks－All Solid Cancers －1

Excess Relative Risk（ERR）

Excess Absolute Risk（EAR）

590.0.5Fitted linear dose response at age 70
following exposure at age 30
Smoothed nonnon-parametric doseresponse0012w e i g h te d co lo n d o s e ( G y)

3

1030
50

3
2
1Age ATB

80.0

1030
50

70.0
60.0
50.0
40.0
30.0
20.0
10.0
0.0

0
25

Colon dose（Gy)EAR Per 10000 PYSv

Age ATB
4

ERR per Sv

excess relative
relative risk risk
Excess

1 .5

3545556575852535

Age at diagnosis4555657585

Age at diagnosis

Statistically significant risk increase is observed also in the dose range of 0 - 0.15 Gy.
(Preston DL et al: Radiat Res 2007; 168: 1-64.)

Site-Specific Risks of Solid Cancers
Site

Atomic Bomb Radiation Health Effects Study－Utilization of Results－ERR/Gy EAR/104PYGy Excess cases

All solid
0.47
Bladder
1.23
Female breast 0.87
Lung0.81
Thyroid
0.57
Colon
0.54
Stomach
0.34
Liver
0.30

52.0
3.2
9.2
7.5
1.2
8.0
9.5
4.3

853
35
147
117
63
7815154* Risks at age 70 following exposure at age 30･ UNSCEAR: United Nations ScientificCommittee on the Effectsof Atomic Radiation･ BEIR Committee: NASNAS-NRC Committee on the
Biological Effects of Ionizing Radiation･ ICRP: International Commission on
Radiological Protection