Dosimetry and toxicity outcomes of knowledge-based volumetric modulated arc therapy for breast cancer: A retrospective cohort analysis.
retrospective_cohort · Level III
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- Record sourced from PubMed, PMID 42468606.
- Also identified by DOI 10.1016/j.radonc.2026.111704.
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Abstract
Volumetric modulated arc therapy (VMAT) in breast radiotherapy has seen limited uptake in routine care. Barriers to adoption include concerns regarding toxicity, dosimetry and low dose wash. There is a lack of modern data to address these concerns. Therefore, the aim of this study is to report on real-world outcomes from a single-class solution implementation of VMAT planned with knowledge-based planning (KBP). A retrospective review of all breast cancer patients undergoing definitive radiotherapy at Royal North Shore Hospital (Sydney, Australia) from June 2020 to June 2023 inclusive was undertaken. All patients were treated with a VMAT technique and planned with KBP. Prospectively collected dosimetry and toxicity data was collated. We identified 484 patients satisfying the inclusion criteria. Doses to constraints easily met international guidelines. For breast/chest-wall alone patients (n = 349), the median average heart dose was <2 Gy for standard fractionation (SF), <1.05 Gy for hypofractionated (HF) and <0.7 Gy for ultrahypofractionated (UHF) patients. The median average ipsilateral lung dose was <7.7 Gy for SF patients, <5.3 Gy for HF patients and <3.6 Gy for UHF patients. Nearly all patients (99%) achieved at least D95% ≥ 95% of the prescribed dose (TD) to the CTV primary. For acute toxicity, there were no clinician-reported high grade (Grade ≥ 3) toxicities and no pneumonitis recorded. This study demonstrates the technical feasibility, excellent dosimetry, and low clinician-reported acute toxicity of a standardised KBP-VMAT approach within a large, real-world cohort. Our approach easily met constraints set in recent international guidelines and randomised controlled trial protocols. While limited by its retrospective, single-arm nature and lack of long-term toxicity outcomes, this study adds to a growing body of literature on the use and outcomes of modern VMAT in breast radiotherapy.