[ RadSafe ] Radiation exposure poses similar risk of first and second cancers in atomic bomb survivors

[ROY HERREN]

Public release date: 15-Sep-2010
Contact: Kristen Woodward
kwoodwar at fhcrc.org
206-667-5095
Fred Hutchinson Cancer Research Center 

Radiation exposure poses similar risk of first and second cancers in atomic bomb 
survivors
First large-scale study to assess how radiation influences risk of multiple 
cancers
SEATTLE – It is well known that exposure to radiation has multiple harmful 
effects – including causing cancer – but until now, it has been unclear to what 
extent such exposure increases a person's risk of developing more than one 
cancer.
The first large-scale study of the relationship between radiation dose and risk 
of multiple cancers among atomic bomb survivors in Hiroshima and Nagasaki, Japan 
reveals a similar risk in the development of first and second subsequent 
cancers.
Christopher I. Li, M.D., Ph.D., and colleagues at Fred Hutchinson Cancer 
Research Center led the study in collaboration with investigators at the 
Radiation Effects Research Foundation in Hiroshima and Nagasaki and the National 
Cancer Institute. The results appear in the Sept. 15 issue of Cancer Research.
"We found that radiation exposure increased the risks of first and second 
cancers to a similar degree," said first author Li, a breast cancer 
epidemiologist and member of the Public Health Sciences Division at the 
Hutchinson Center. "People exposed to radiation who developed cancer also had a 
high risk of developing a second cancer, and the risk was similar for both solid 
tumors and leukemias in both men and women, regardless of age at exposure or 
duration between first and second primary cancers," he said. 

The association between radiation exposure and risk of second cancers was 
particularly significant for radiation-sensitive cancers, such as those of the 
lung, colon, breast, thyroid and bladder, as well as leukemia.
For the study, the researchers analyzed data from participants in the Life Span 
Study, a group of atomic bomb survivors in Hiroshima and Nagasaki who were 
followed from 1950, five years after the bombings, to 2002, the most recent year 
through which Hiroshima and Nagasaki cancer registry data were complete. The 
study followed 10,031 primary cancer survivors, among whom 1,088 went on to 
develop second primary cancers.
Stomach, lung, liver and female breast cancers were the most commonly diagnosed 
first and second primary cancers.
"Our findings suggest that cancer survivors with a history of radiation exposure 
should continue to be carefully monitored for second cancers," Li said. 

In addition to clinical implications for cancer patients and others exposed to 
significant amounts of radiation, such research is essential to developing 
radiation protection limits and standards for occupational exposures, as well as 
planning for the consequences of widespread radiation exposure in the general 
population in the event of a nuclear accident, nuclear war or "dirty bomb" 
terrorist attack.
"We greatly appreciate having the opportunity to conduct this unique research 
with our Japanese colleagues who, through innumerable publications, have truly 
transformed the tragedy of the atomic bombings to fundamental scientific 
advancements that have impacted radiation protection standards and policies 
worldwide," Li said.
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The Radiation Effects Research Foundation (RERF) in Japan is a private, 
nonprofit foundation funded by the Japanese Ministry of Health, Labour and 
Welfare and the U.S. Department of Energy through the National Academy of 
Sciences. RERF funded this research along with the National Cancer Institute and 
the National Institutes of Health Division of Cancer Epidemiology and Genetics.
At Fred Hutchinson Cancer Research Center, our interdisciplinary teams of 
world-renowned scientists and humanitarians work together to prevent, diagnose 
and treat cancer, HIV/AIDS and other diseases. Our researchers, including three 
Nobel laureates, bring a relentless pursuit and passion for health, knowledge 
and hope to their work and to the world. www.fhcrc.org

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