While conventional radiation therapy can be effective for patients with breast cancer, it carries with it risk of damage to the heart and lungs. Proton beam radiotherapy, a specialized type of external beam radiation that precisely targets a tumor with high doses of radiation while minimizing damage to nearby tissue and critical organs, shows promise as an alternative for some patients. In a phase 2 study published recently in the Journal of Clinical Oncology, a team of researchers at Massachusetts General Hospital (MGH), led by Rachel B. Jimenez, MD, found that in patients with nonmetastatic breast cancer requiring postoperative radiation therapy, proton beam radiotherapy has low toxicity, with efficacy comparable to conventional radiotherapy. In this interview with i3 Health, Dr. Jimenez discusses the importance of her study's results and the additional research that is underway.
Can you comment on the significance of your study's findings concerning proton beam radiotherapy for patients with breast cancer who require regional nodal irradiation?
Rachel B. Jimenez, MD: Conventional radiotherapy for women with breast cancer has been associated with an increased risk of cardiovascular disease. This is a particular concern among women who require radiation to their internal mammary lymph nodes, the lymph nodes in the center of the chest, because of the proximity of these lymph nodes to the heart. Proton beam radiation has different physical properties than conventional radiation, permitting superior avoidance of the heart without compromising treatment quality. This study is the first prospective trial of proton beam radiation for breast cancer patients requiring regional lymph node irradiation, so it is significant that it demonstrates a safety and efficacy profile that appears at least as good as conventional radiotherapy. These results support further study into the potential long-term cardiovascular advantages of proton beam radiation for breast cancer patients.
How does proton beam radiotherapy compare with conventional radiotherapy in terms of safety and efficacy?
Dr. Jimenez: This study demonstrates that proton beam radiotherapy appears to be equally safe and effective in comparison with conventional radiotherapy for women who require regional nodal irradiation for breast cancer, and it suggests that proton beam therapy may have the potential to decrease late cardiac toxicity, given the very low cardiac exposures achieved in this study cohort.
Is further research underway for proton beam radiotherapy in this population?
Dr. Jimenez: Yes, this study provided the preliminary data to support a national phase 3 randomized clinical trial, called RadComp, that compares proton beam radiation to conventional radiation in women with non-metastatic breast cancer who require radiation to the internal mammary nodes. The primary end point of this study is the 10-year rate of major cardiac events. RadComp is actively enrolling patients at 65 centers around the country, and Massachusetts General Hospital is a leading institution in the accrual to this trial. Additionally, at MGH, we also have other correlative studies in the breast cancer population underway comparing proton therapy to conventional radiation in regard to additional quality-of-life concerns, including exercise tolerance, cosmetic outcomes, endocrine function, and lymphedema.
What advice can you give to community radiation oncologists and medical oncologists treating patients with nonmetastatic breast cancer?
Dr. Jimenez: Please consider your patients with high-risk breast cancer for a clinical trial, including RadComp. This study was successful largely due to the thoughtful referrals from physicians, both here at MGH and in the community, who were proactive in advocating for their patients and who pursued studies that could potentially improve their patients' outcomes and quality of life. Many insurers have agreed to cover proton therapy on a clinical trial to support scientific progress in this arena.
About Dr. Jimenez
Rachel B. Jimenez, MD, is a radiation oncologist at MGH; she is also the Associate Director of Translational Research for Radiation Oncology at MGH and the MGH Program Director for the Harvard Radiation Oncology Program. Her clinical and research interests lie in the area of radiation treatment for breast cancer, with a focus on proton beam therapy. She has authored and co-authored numerous peer-reviewed publications concerning these topics and concerning both patient-doctor communication and medical education.
For More Information
Jimenez RB, Hickey S, DePauw N, et al (2019). Phase II study of proton beam radiation therapy for patients with breast cancer requiring regional nodal irradiation. J Clin Oncol. [Epub ahead of print] DOI:10.1200/JCO.18.02366
Clinicaltrials.gov (2019). Pragmatic randomized trial of proton vs. photon therapy for patients with non-metastatic breast cancer: a radiotherapy comparative effectiveness (RADCOMP) consortium trial. NLM identifier: NCT02603341.