Baptist Health South Florida

New Study Dispels Myths About Effects of Radiation Therapy on Breast Cancer Patients’ Hearts

March 3, 2022

BOCA RATON– March 3, 2022 — A landmark study led by a Lynn Cancer Institute breast cancer specialist offers conclusive evidence that, for patients with HER-2 positive breast cancer who are treated with both chemotherapy and modern radiation therapy (RT), the radiation itself brings little or no additional risk of damage to the heart, despite this vital organ’s close proximity to the breast being treated with RT.

The study, said to be the largest of its kind, demonstrates that adding modern RT to treatment results in no significant increase in cardiotoxicity in women with HER-2 positive breast cancer, according to its principal investigator, Youssef Zeidan, M.D., Ph.D., a radiation oncologist with Lynn Cancer Institute at Boca Raton Regional Hospital, which is part of Baptist Health South Florida.

For the past 20 years, the standard of care for this type of HER-2 positive breast cancer has included chemotherapy and a targeted antibody, trastuzumab. While remarkably effective, this treatment also has the potential to cause damage to the heart.

“Trastuzumab has been a game-changer for the treatment of HER-2 positive breast cancer, which used to be considered very aggressive and fatal,” says Dr. Zeidan. “Women diagnosed with this cancer today have a far better chance of surviving than they did 20 years ago.”

Dr. Zeidan, along with his co-investigators in Belgium, Philip Poortmans, M.D., and Evandro de Azambuja, M.D., undertook analysis of 3,321 HER-2 positive breast cancer patients from across Europe, UK, Australia and Canada who had been treated with trastuzumab, with or without RT. “Cardiac function for each patient had been closely monitored over a median follow-up period of 11 years,” Dr. Zeidan notes.

According to Dr. Zeidan, every patient has the right to know what health risks they may incur years down the road from their treatment, whether they have chemotherapy or RT or a combination of both. “They should know exactly where their risk is coming from, and what each one contributes in terms of overall cardiotoxicity,” Dr. Zeidan says.

The team’s research revealed that, over a 10-year period following treatment, the incidence of having a cardiovascular event such as a heart attack was minimal (just 0.6 to 1.0 percent). “Across all three groups,” Dr. Zeidan emphasizes. “We were surprised that incremental toxicity from RT was so extremely low. It really had no additional effect on the heart above the cardiotoxicity they had already experienced from their baseline chemotherapy.”

Dr. Zeidan says he hopes the study’s findings can help support and advance care protocols for HER-2 positive breast cancer. “This is the largest study to date to answer this specific question, and the data should provide peace of mind for both the patient and the physician.”

About the Eugene M. & Christine E. Lynn Cancer Institute

The Eugene M. & Christine E. Lynn Cancer Institute is part of Baptist Health South Florida, the largest healthcare organization in the region, with 11 hospitals, more than 23,000 employees, 4,000 physicians and 100 outpatient centers, urgent care facilities and physician practices spanning across Miami-Dade, Monroe, Broward and Palm Beach counties. Baptist Health has internationally renowned centers of excellence in cancer, cardiovascular care, orthopedics and sports medicine, and neurosciences. In addition, it includes Baptist Health Medical Group; Baptist Health Quality Network; and Baptist Health Care On Demand, a virtual health platform. A not-for-profit organization supported by philanthropy and committed to its faith-based charitable mission of medical excellence, Baptist Health has been recognized by Fortune as one of the 100 Best Companies to Work For in America and by Ethisphere as one of the World’s Most Ethical Companies. For more information, visit and connect with us on FacebookInstagramTwitter and LinkedIn.




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