Dosimetric Correlates of Acute Toxicities for Moderate Hypofractionated Whole-Breast Irradiation: Implications for ASTRO Planning Guidelines

Vishruta A Dumane; Juliana Runnels; Mira Cohen; Weijia Fu; Andrew Jackson; Jing Wang; Kaida Yang; Madhu Mazumdar; Tian Liu; Sheryl Green

doi:10.1016/j.adro.2026.102031

Dosimetric Correlates of Acute Toxicities for Moderate Hypofractionated Whole-Breast Irradiation: Implications for ASTRO Planning Guidelines

Adv Radiat Oncol. 2026 Mar 21;11(6):102031. doi: 10.1016/j.adro.2026.102031. eCollection 2026 Jun.

Authors

Affiliations

¹ Department of Radiation Oncology, Icahn School of Medicine at Mount Sinai, New York, New York.
² Department of Population Health Science and Policy, Icahn School of Medicine at Mount Sinai, New York, New York.
³ Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York.

Abstract

Purpose: ASTRO's 2018 guidelines for hypofractionated whole-breast irradiation (HF WBI) recommend limiting high-dose regions to improve dose homogeneity and minimize toxicity. However, correlation of these guidelines with clinical outcomes remains limited. This study investigates the relationship between dose-volume parameters and acute toxicities including pain, erythema, edema and moist desquamation in patients treated with HF WBI in accordance with ASTRO 2018 guidelines.

Methods and materials: We retrospectively reviewed patients treated from 2018 to 2023 with HF WBI (42.56 Gy in 16 fractions or 40.05 Gy in 15 fractions) between 2018 and 2023 using 3-dimensional conformal field-in-field planning. All plans adhered to ASTRO constraints (V105% < 200 cm³; V107% < 2 cm³). Acute toxicities were prospectively scored using the Common Terminology Criteria for Adverse Events V5.0 at weekly on-treatment visits (OTVs) and at 1 month follow-up. Logistic regression analyses identified predictors of grade ≥ 2 toxicities.

Results: 600 patients were treated with HF WBI. Of those patients, 82.3% received a dose of 42.56 Gy in 16 fractions, whereas the remaining received 40.05 Gy in 15 fractions. Three-dimensional field-in-field planning was used in all patients and 73.7% received a boost. Moderate-to-severe pain (grade ≥ 2) occurred in 29.7% of patients during treatment despite compliance with ASTRO guidelines. In contrast, grade ≥ 2 erythema, edema, and moist desquamation were observed in <5% of patients. Multivariate analysis identified V105 % (cm³) ≥ 50 cm³, V105 % (%) ≥ 5% and body mass index ≥ 30 as independent predictors of grade ≥ 2 pain, which decreased by 30% when V105 % (cm³) < 50 cm³ and by 18.5% when V105 % (%) < 5%.

Conclusions: Although skin related toxicities were infrequent and largely resolved by 1 month, pain remained a prevalent side effect of HF WBI. These findings suggest that ASTRO's current V105% thresholds may be too permissive for pain mitigation. Stricter limits of V105% (cm³) < 50 cm³ and V105% (%) < 5% may better protect patients from treatment-related discomfort and warrant consideration in future guideline updates.