Researchers Call for Additional Follow-up to Assess Cardiac Toxicity From Breast Cancer Radiation Treatments

Researchers are questioning the current belief that modern radiation therapy treatments for breast cancer have succeeded in decreasing cardiac toxicity because modern studies significantly decreased follow-up.

Older radiation therapy studies related the higher cardiac toxicity to larger fraction sizes, wide fields and orthovoltage energy, according to Senem Demicri, M.D., et al., in the March 2009 Red Journal. Studies prior to 1980 followed cases more than a decade, while current ones that show less toxicity report less than 10 years of follow-up, the authors state in, "Radiation-induced Cardiac Toxicity After Therapy for Breast Cancer: Interaction Between Treatment Era and Follow-up Duration." The study was published in the March issue of the International Journal of Radiation Oncology Biology & Physics.

"The comparisons between the "older" and "modern" trials are confounded by the longer follow-up time in the "older" trials," the authors state.

Demicri et al define the "older" studies as patient accrual start years before 1980 and cut off the follow-up at 10 years to segregate and analyze the trials. All the older trials reported excess cardiac toxicity, with a median follow-up of 10 years to 15 years. The more modern trials reported no excess toxicity risk, according to the authors.

"Additional follow-up is needed to ensure that modern methods effectively reduce cardiac toxicity. Continued diligence to minimize cardiac exposure remains prudent," concluded the authors.

The study can be found at www.redjournal.org.