Does radiation therapy cause second cancers?

The link between radiation and cancer was confirmed many years ago through studies of the survivors of the atomic bombs in Japan, the exposures of workers in certain jobs, and patients treated with radiation therapy for cancer and other diseases.

Some cases of leukemia are related to past radiation exposure. Most develop within a few years of exposure, with the risk peaking at 5 to 9 years, and then slowly declining. Other types of cancer that develop after radiation exposure have been found to take much longer to show up. These are solid tumor cancers, like breast or lung cancer. Most are not seen for at least 10 years after radiation exposure, and some are diagnosed even more than 15 years later.

Radiation therapy techniques have steadily improved over the last few decades. Treatments now target the cancers more precisely, and more is known about setting radiation doses. These advances are expected to reduce the number of secondary cancers that result from radiation therapy. Overall, the risk of second cancers is low and must be weighed against the benefits gained with radiation treatments.

To learn more about this, see Second Cancers in Adults.

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Last Medical Review: October 27, 2014 Last Revised: October 27, 2014

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