In a study reported in The Lancet Oncology, Kirby et al identified real-world heart and lung radiation doses associated with English National Health Service (NHS) radiotherapy treatment plans in breast radiotherapy practices.
Study Details
The study involved data from 26,236 eligible patients accessed from 48 of 49 NHS radiotherapy centers in England between December 2024 and April 2025. Radiotherapy plans were stratified by laterality: breast, chest wall, or partial-breast only (26 Gy in 5 fractions); breast or chest wall and axilla (40 Gy in 15 fractions); and breast or chest wall and axilla and internal mammary chain (40 Gy in 15 fractions). Use of field-based vs volumetric-modulated arc therapy was assessed. Dose-volume heart and lung metrics were compared with national scorecards derived from UK trials.
Key Findings
For breast, chest wall, or partial-breast-only treatments, 10,012 (99.8%) of 10,031 left-sided cases and 6,961 (99.9%) of 6,962 right-sided cases achieved mean heart doses (MHDs) below 2 Gy: median MHD = 0.57 Gy, interquartile range (IQR) = 0.43 to 0.74 Gy for left-sided cases, and 0.25 Gy, IQR = 0.18 to 0.36 Gy for right-sided cases.
For nodal plans including internal mammary chain, median MHDs were 3.3 Gy (IQR = 2.3–4.5 Gy) for left-sided cases and 2.3 Gy (IQR = 1.1–3.7 Gy) for right-sided cases. A total of 2,405 (98.3%) of 2,446 plans met the 6-Gy constraint.
A total of 8,697 (92.1%) of 9,448 left-sided breast, chest wall, or partial-breast plans met the optimal lung dose constraint—ie, the volume of ipsilateral lung receiving > 7.8 Gy = ≤ 15%. A total of 1,155 (96.0%) of 1,203 left-sided nodal-internal mammary chain plans met the mandatory lung dose constraint—ie, volume of lung receiving > 17 Gy = ≤ 35%.
Volumetric-modulated arc therapy was used in 65 (0.3%) of 21,119 breast-only plans, 276 (10.5%) of 2,638 nodal-noninternal mammary chain plans, and 1,738 (70.1%) of 2,479 internal mammary chain plans. Volumetric-modulated arc therapy was found to deliver superior target volume coverage but higher MHDs compared with field-based techniques.
The investigators concluded: “This breast radiotherapy dosimetry audit shows the feasibility of high-quality, large-scale, real-world dosimetric collection and evaluation across the NHS in England. Heart and lung doses predominantly met constraints and were comparable to international benchmarks. However, dosimetric variation existed between centers, particularly in volumetric-modulated arc therapy planning, identifying opportunities for quality improvement.”
Anna Kirby, FRCR, MD, of Royal Marsden NHS Foundation Trust, Sutton, UK, is the corresponding author for The Lancet Oncology article.
DISCLOSURE: The study was funded by NHS England. For full disclosures of the study authors, visit thelancet.com.
