Depending on their treatment, childhood survivors of cancer may be more likely to have breast cancer in adulthood, a new retrospective study discovered. According to the report, the association lies in the use of combination anthracyclines and radiotherapy to treat the pediatric cancer.
Female survivors of childhood cancer who have been treated with high doses of anthracyclines have a lifetime breast cancer risk similar to that of people with known hereditary breast cancer risk gene mutations. Radiation to the chest area is already well established as a factor that increases the risk of breast cancers in survivors, but less is known about how anthracyclines contribute to this risk. Two previous studies have also suggested a link.
“Chest irradiation for childhood cancer is associated with increases in breast cancer risk. Growing evidence suggests that anthracyclines increase this risk, but the outcome of combined anthracycline use and radiotherapy has not been studied,” the researchers stated. Their findings appeared in JAMA Pediatrics.
The above study included 14,358 five-year survivors of childhood cancer who were diagnosed between 1970 and 1986 and followed through Dec. 31, 2016. Of the 271 patients with breast cancer within the North America Childhood Cancer Survivor Study, the combination of anthracyclines and radiotherapy doses to the breast was associated with increased breast cancer risks and was greater than the sum of their effects, consistent with an additive interaction.
Another study, published by researchers from St Jude Children’s Research Hospital in the Journal of Clinical Oncology, followed 1467 women enrolled in the St Jude Lifetime Cohort Study (SJLIFE) and found 68 breast cancers across 56 individuals (patients were a median age of 38.6 years). The study participants were all older than 18 years and were 10 or more years from diagnosis.
“There have been a number of studies looking at breast cancer risk, and most have identified radiation as the predominant risk factor,” said Matthew Ehrdhart, MD, MS, lead author of the study and member of the Cancer Survivorship division at St Jude’s. “We observed a similar risk associated with anthracyclines across multiple statistical models that adjusted for other chemotherapy exposures, radiation, and genetic predisposition, and therefore, feel confident that anthracyclines uniquely contribute to breast cancer risk in childhood cancer survivors,” he added.
Researchers in these various studies concluded that the use of combination anthracyclines and radiotherapy to treat childhood cancers may be associated with a greater risk for breast cancer compared to using neither treatment; they stated that the findings may be useful in discussing guidelines for childhood survivors of cancer.