(RxWiki News) Sometimes, radiation can be a lifesaving cancer treatment. But radiation may also increase the risk for developing another cancer — and new research suggests this might have happened to some children years after radiation treatment.
Treatment of Wilms tumor, a rare childhood kidney cancer, can include radiation treatments to the chest. Because radiation is thought to increase the risk for other cancers, a group of researchers studied girls with Wilms tumor to see whether they were more likely to develop breast cancer.
Girls treated with radiation directed at the chest had a greatly increased risk for breast cancer as young women — compared to those who did not receive radiation.
Norman E. Breslow, PhD, of the University of Washington and the Fred Hutchinson Cancer Research Center in Seattle, and colleagues wrote a paper on the research findings.
Advancements in the treatment of Wilms tumor have raised the cure rate to nearly 90 percent, the study authors wrote. Treatments can include radiation to the chest or stomach.
Dr. Breslow and team reviewed data on 2,492 girls with Wilms tumor. The patients ranged in age from newborn to 19 years old. The study authors noted whether the girls received radiation therapy for their cancer.
The team continued to collect data on patients who lived past age 15 to see whether they developed breast cancer.
"I applaud the authors of this important study analyzing the long-term risks of developing a well-known secondary malignancy, breast cancer, in pediatric cancer patients who undergo thoracic radiation," said Brian Lawenda, MD, National Director of Integrative Oncology and Cancer Survivorship, 21st Century Oncology and Founder of Integrative Oncology-Essentials. "For many years, oncologists have been aware of the increased risk of developing breast cancer in adult survivors of pediatric lymphomas who received thoracic radiation therapy as part of their treatment."
Dr. Breslow and his team found 29 cases of breast cancer among the patients. Twenty-five of the cancers were in women younger than 40.
The researchers calculated that the risk of getting breast cancer by age 40 for the women in this study was more than 27 times that of the average woman.
Most of the breast cancer was in women who had chest radiation. Of the 369 patients who received chest radiation, 16 developed breast cancer.
"Follow-up guidelines have generally recommended breast imaging (i.e. mammography) starting at the age of 25 years or 8 years after thoracic [chest] radiation therapy in those who received a radiation dose of 20 Gy or higher. Thanks to this study, we now know that thoracic radiation therapy doses as low as 12 Gy are associated with a significant increase in the risk of developing breast cancer in adult survivors of pediatric Wilms tumor," said Dr. Lawenda.
"Furthermore, any diagnosis of WT appears to increase the risk of developing breast cancer as an adult even without having received prior radiation therapy to the chest. It is believed that this increased risk of breast cancer in those without prior radiation therapy is due to associated chromosomal [genetic] abnormalities often co-existing with a diagnosis of WT that predispose to the eventual development of breast cancer.
In a related editorial, Jennifer B. Dean, MD, and Jeffrey S. Dome, MD, PhD, of Children's National Health System in Washington, DC, said "The take-home message is that [doctors who treat childhood cancer] should closely evaluate their female survivors of [Wilms tumor] for risk factors for the development of breast cancer."
Drs. Dean and Dome noted that only about half of cancer survivors at risk for breast cancer are screened as recommended. They urged better education for survivors and health care providers to increase screening.
"[Dr. Breslow and colleagues] have provided us important information that should prompt changes to the follow-up guidelines for patients with a history of Wilms tumor (with or without prior thoracic radiation therapy to doses less than 20 Gy). Breast cancer screening should be implemented in all patients in this high-risk population," Dr. Lawenda said.
This study and editorial were published online Oct. 27 in Cancer.
The National Institutes of Health funded the research. The authors disclosed no conflicts of interest.