Drop in radiation dose leads to fewer subsequent cancers in children

Paul Basilio, MDLinx | March 01, 2017

Childhood cancer survivors are living longer than ever, and new research shows they are also less likely to develop subsequent neoplasms while still young.

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Gregory T. Armstrong, MD, MSCE, the principal investigator of the Childhood Cancer Survivor Study. Image courtesy of St. Jude Children's Research Hospital/Seth Dixon.

The decline followed a sharp drop in therapeutic radiation doses in the treatment of childhood cancers.

Between the 1970s and 1990s, the percentage of pediatric cancer patients treated with radiation fell from 77% to 33%, and the median radiation dose decreased from 30 Gy to 26 Gy. In addition, the likelihood of developing second cancers within 15 years of the first diagnosis also decreased.

The study included greater than 23,000 five-year survivors from the Childhood Cancer Survivor Study. The survivors were treated at 27 medical centers in the US and Canada.

The most common initial diagnoses included Hodgkin lymphoma, acute lymphoblastic leukemia, and astrocytoma. During a mean follow-up of 20.5 years, 1639 survivors developed 3115 subsequent neoplasms, including 1026 malignancies, 233 benign meningiomas, and 1856 nonmelanoma skin cancers. The most common subsequent malignancies were breast and thyroid cancers.

Gregory Armstrong, MD, of the St. Jude Department of Epidemiology and Cancer Control, headed the study.

“The most ominous late effect of pediatric cancer treatment is a second malignancy,” he said. “This study shows efforts to reduce the late effects of treatment are paying off.”

Changes in radiation dose were associated with a reduced risk for subsequent malignancies, meningiomas, and non-melanoma skin cancers.

“The risk of second cancers for survivors increases with age, so it is good to see the reduction emerging early in survivorship while survivors are still young,” Dr. Armstrong Added.

The federally funded study was based at St. Jude in Memphis, TN.

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