Acute radiation side effects of proton versus photon therapy following surgery for early breast cancer, a sub-study of the randomised controlled DBCG Proton Trial
In brief
Proton therapy triples moderate skin toxicity (71% vs 20%) in early breast cancer
In the DBCG Proton Trial sub-study, 84 patients receiving proton radiotherapy had grade 2-3 dermatitis in 71% of treated breasts, compared with 20% after photon therapy, while itching and pain were also more common but resolved within weeks. Respiratory, fatigue and arm-shoulder side effects were similar, indicating proton treatment is feasible despite higher transient skin reactions.
- Journal
- International journal of radiation oncology, biology, physics (Q1)
- Published
- 14 August 2026
- Study design
- Randomized controlled trial
- Evidence level
- Level 1, High (CEBM 1b)
- Authors
- Kristine Wiborg Høgsbjerg, Stine Elleberg Petersen, Else Maae, Louise Wichmann Matthiessen, Mette Møller, Maja Vestmø Maraldo, et al.
- PMID
- 42600707
- DOI
- 10.1016/j.ijrobp.2026.08.011
Why clinicians should know about it
- Picked for Radiation Oncology (top studies of the week, 11 October 2026): Acute side effects, proton vs photon breast RT
- Picked for Radiology, Radiation Oncology, Nuclear Medicine, Medical Physics and Imaging (top studies of the week, 11 October 2026): Proton vs photon acute side‑effects in breast cancer trial
Abstract
PURPOSE: Proton therapy (PT) is associated with favorable dosimetric characteristics compared with photon radiotherapy (γRT) in invasive breast cancer; however, clinical evidence on acute toxicity remains limited. This study aims to compare acute treatment-related side effects between moderately hypofractionated PT and γRT in breast cancer. MATERIALS AND METHODS: The DBCG PROTON Trial - Acute Side Effects was a preplanned sub-study of the national, phase III randomised trial, the DBCG Proton Trial. Patients with invasive breast cancer or DCIS scheduled for adjuvant radiotherapy, who were expected to receive a high cardiac and/or pulmonary dose based on γRT planning CT, were randomised 1:1 to PT or γRT. Acute side effects were prospectively assessed during radiotherapy and up to 6 months post-treatment. Outcomes included skin -related side effects, respiratory symptoms, dysphagia, fatigue, and arm/shoulder side effects. RESULTS: A total of 167 patients (186 treated breasts) were included (PT 84, γRT 83). Skin-related side effects peaked at week five, with higher grade 2-3 dermatitis (71% PT vs 20% γRT), pruritus (20% vs 5%), and local pain (17% vs 4%) after PT compared to γRT. All skin-related grade 2-3 side effects were transient, resolving to grade 0-1 within 2-4 weeks. Respiratory symptoms, dysphagia, and fatigue were mild and similar between groups. Clinically relevant arm/shoulder morbidity was rare. No treatment discontinuations due to side effects were observed. CONCLUSION: Acute side effects after breast cancer radiotherapy were primarily skin-related, higher but transient after PT compared to γRT. Non-skin-related side effects, including respiratory, fatigue, and arm/shoulder morbidity, were comparable between PT and γRT. These prospective data, using modern techniques and moderate hypofractionation, suggest that PT is a feasible and clinically acceptable treatment approach for adjuvant treatment of invasive breast cancer or DCIS, while acknowledging the higher incidence of transient acute skin toxicity.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.