WEDNESDAY, Sept. 15 (HealthDay News) -- Radiation exposure increases the risk that cancer survivors will go on to develop another malignancy, finds a new study.

It was known that radiation exposure can cause cancer but it wasn't known whether it increases a person's risk of developing more than one. In order to find out, American and Japanese researchers analyzed data from more than 10,000 survivors of the atomic bomb attacks on Hiroshima and Nagasaki who developed primary cancers.

"We found that radiation exposure increased the risks of first and second cancers to a similar degree," study first author Dr. Christopher Li, a breast cancer epidemiologist and a member of the Public Health Sciences Division at the Fred Hutchinson Cancer Research Center in Seattle, said in a center news release.

"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," Li said.

The link between radiation exposure and second cancers was especially strong for radiation-sensitive cancers such as leukemia and tumors of the lung, colon, breast, thyroid and bladder.

The study appears in the Sept. 15 issue of the journal Cancer Research.

"Our findings suggest that cancer survivors with a history of radiation exposure should continue to be carefully monitored for second cancers," Li said.

He also thanked his Japanese colleagues for their collaboration. "Through innumerable publications, [they] have transformed the tragedy of the atomic bombings to fundamental scientific advancements that have impacted radiation protection standards and policies worldwide," Li said.

More information

The American Cancer Society has more about radiation exposure and cancer.