Survivors of childhood cancers have fewer secondary cancers, according to new research from the Masonic Cancer Center, University of Minnesota and St. Jude Children’s Research Hospital. Compared with those diagnosed in the 1970s, patients diagnosed after 1990 are experiencing better outcomes. Researchers believe the difference comes from a reduction in exposure to therapeutic radiation.

The results were published in the Journal of the American Medical Association. Work was led by the Masonic Cancer Center, University of Minnesota in partnership with investigators at St. Jude Children’s Research Hospital. It utilized data from the Childhood Cancer Survivor Study (CCSS).

“It’s quite exciting. We’ve known for several years that radiation therapy puts survivors at high–risk for secondary cancers, and treatments have been modified to reduce radiation exposure,” said Lucie Turcotte, MD, lead researcher, assistant professor of pediatrics in the University of Minnesota Medical School and member of the Masonic Cancer Center, University of Minnesota. “Still, no one has shown reducing the exposure has reduced subsequent cancer risk. That’s what we’ve done in this paper.”

This project utilized data from CCSS, the largest cohort of North American cancer survivors. Turcotte and her collaborators examined more than 23,000 survivors with a first diagnosis between 1970 and 1999 who had participated in the cohort over time. By looking at long term data, they were able to look at radiation exposure (1970s, 77% vs. 1990s, 33%) and determined the 15–year incidence of subsequent cancers decreased in each decade of the initial diagnosis – those diagnosed in the 1970s saw a 2.1% rate of subsequent cancers, while those diagnosed in the 1990s saw 1.3% rate.

“This study is unique because we were able to look comprehensively at treatment exposure data and validated subsequent cancer data,” said Joseph Neglia, MD, MPH, senior author and head of the Department of Pediatrics in the UMN Medical School. He is also a Masonic Cancer Center member. “This level of in–depth and longitudinal data allows us to make a much clearer analysis.”

The team plans to continue researching this issue, focusing on increasing understanding of specific cancer therapy agents and their effects, as well as looking more closely at chemotherapy–radiation interactions impacting secondary cancer risks. Following the cohort in this study will also be of interest, to see how the more recent survivors do as they age.

“All the efforts to modify treatment of pediatric cancer in order to reduce late effects while maintaining or improving cure rates are paying off,” said Gregory Armstrong, MD, of St. Jude Children’s Research Hospital and principal investigator of the Childhood Cancer Survivor Study. “This study shows that for the most ominous late effect of treatment, second cancers, the risk has been reduced for childhood cancer survivors from the modern treatment era.”