ASTRO 2024: Hypofractionated vs Conventional Regional Nodal Irradiation in Treating Invasive Breast Cancer

By: Chris Schimpf, BS
Posted: Friday, October 4, 2024

Hypofractionated regional nodal irradiation—which delivers higher doses of radiation in fewer sessions than conventional radiation plans—may reduce adverse effects in patients undergoing radiation treatment for invasive breast cancer, according to research presented at the 2024 American Society for Radiology Oncology (ASTRO) Annual Meeting (Abstract 100). Karen Hoffman, MD, FASTRO, of The University of Texas MD Anderson Cancer Center, Houston, and colleagues found in the primary outcome analysis of their phase III clinical trial that the hypofractionated approach reduced the risk of both physician-reported lymphedema and grade 2 or higher toxicity, compared with standard regional nodal irradiation. It also demonstrated a low risk of local-regional recurrence.

A total of 324 patients with cT0–T3, N0–N2a, or N3a invasive breast cancer for whom regional nodal irradiation was recommended were included in the study, drawn from five treatment centers and enrolled between 2017 and 2022. Participants were randomly assigned to receive either standard regional nodal irradiation (50 Gy to breast/chest wall and 45 Gy to regional nodes) or hypofractionated regional nodal irradiation (40.05 Gy to breast/chest wall and 37.5 Gy to regional nodes). The median follow-up was 4.75 years, and the researchers noted that clinical-pathologic covariates were well balanced between the two groups.

The investigators reported that perometry-assessed lymphedema was less common among those who received the hypofractionated treatment (29%) than the standard treatment group (36%), but the difference was not statistically significant (P = .24). In contrast, physician-assessed lymphedema was significantly less common with the hypofractionated approach than with the conventional one (15% vs 27%; P = .009). In addition, patients who underwent the hypofractionated treatment were less likely to experience any grade 2 toxicity (52% vs 78%; P < .001). Finally, 5-year risk of local-regional recurrence was 3% among those who received hypofractionated treatment and 2% among those who received standard treatment (P = .48).

Disclosure: For full disclosures for Dr. Hoffman, visit astro2024.eventscribe.net.

2024 ASTRO Annual Meeting

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