Proton Beam Radiotherapy for Nodal Irradiation in Patients With Breast Cancer
Posted: Tuesday, December 24, 2019
The results of a phase II trial of 70 patients with breast cancer “pave the way for randomized studies to compare proton beam radiation therapy with standard radiation therapy,” according to Rachel B. Jimenez, MD, of Massachusetts General Hospital, Boston, and colleagues. The Journal of Clinical Oncology published this study of the safety and efficacy of this radiation technique in patients with nonmetastatic breast cancer who required regional nodal irradiation but were considered suboptimal candidates for conventional radiation therapy. In addition to being associated with low toxicity, proton beam radiation therapy did not contribute to early cardiac changes and provided a rate of disease control similar to that of standard radiation therapy.
The 69 evaluable patients (median age = 45 years; 94% with stage II/III breast cancer) required postoperative radiation therapy to the breast/chest wall and regional lymphatics. “The primary endpoint was the incidence of grade 3 or higher radiation pneumonitis or any grade 4 toxicity within 3 months of radiation therapy,” noted the team. At a median follow-up of 55 months, no grade 4 toxicities had occurred, and 1 and 0 patients had developed grade 2 and grade ≥ 3 radiation pneumonitis, respectively.
Proton beam radiation therapy is acclaimed for its potential to precisely deliver high radiation doses to tumors with minimal damage to surrounding tissue. In this study, “among 62 surviving patients, the 5-year rates for locoregional failure and overall survival were 1.5% and 91%, respectively,” described Dr. Jimenez and co-researchers. “No significant changes in echocardiography or cardiac biomarkers after radiation therapy were found.”
“Future research will provide needed information about the potential long-term normal tissue–sparing benefits of this complex treatment modality compared with conventional radiation,” the investigators concluded.
Disclosure: For full disclosures of the study authors, visit ascopubs.org.