‘Radiation Is Not the Enemy’

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“I want to make very clear that radiation is not the enemy,” Monika Metzger, MD, MSc, emphasized in discussing a study she led on the integration of brentuximab vedotin into the front-line treatment of pediatric patients with high-risk Hodgkin lymphoma. The study yielded excellent results while allowing a significant reduction in radiation exposure.

“It is very important to understand that it is not my goal to completely eliminate radiation. To do that, I would have to be so aggressive with my front-line treatment that I would be obviating the benefits of what we have gained,” Dr. Metzger said in an interview with The ASCO Post. “To identify those patients who would benefit the most from radiation—that is the goal. We aim to find out who needs radiation and give it in as targeted a way as possible to prevent that patient from relapsing.” Dr. Metzger is a pediatric oncologist and Director for the Central and South America Region, Global Pediatric Medicine Department, St. Jude Children’s Research Hospital, Memphis.

Threefold Reduction

As noted in the study report: “While maintaining efficacy, this trial significantly reduced the volume of irradiated tissue threefold compared with our previous trial, eliminated mandatory radiation for bulky disease, and reduced normal tissue exposures.”

The report also noted that although “response-adapted low-dose radiation has become a hallmark of pediatric Hodgkin lymphoma trials, radiation was historically applied in an all-or-nothing approach using involved fields, where the patient qualifies for no radiation to any site (or only bulky mediastinal masses) or radiation to all involved sites, even if only one site did not achieve the desired early response to therapy.” According to Dr. Metzger, “That approach is not being used in any of the currently open pediatric trials.”

Protons and Photons

Although comparing proton-beam radiation vs photon-based radiation was not part of the study design, the researchers did make this observation: “Both organ-specific doses and general tissue exposures were lower in patients treated with proton-beam therapy, which resulted in a near 10-fold further reduction in mean breast exposure, which could possibly affect late toxicities and second malignancies.”

Dr. Metzger noted: “Not every institution has access to proton-beam radiation, and there are only two or three institutions in the country that can give protons to children.” St. Jude is one of them, and “we do use it whenever we find it is in the best interest of the patient, because it is not always the best approach. It is a case-by-case decision to treat with protons vs photons.” 

DISCLOSURE: Dr. Metzger has received research funding from Seattle Genetics.

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Integrating the antibody-drug conjugate brentuximab vedotin into the front-line treatment of pediatric patients with high-risk Hodgkin lymphoma “facilitated significant reduction in radiation exposure and yielded excellent outcomes,” Monika Metzger, MD, MSc, Director for the Central and South...