Abstract / Summary
Background/Objectives: Tumours abutting or involving the brachial plexus can cause pain and neurological deficits. We evaluated six-fraction ultra-hypofractionated radiotherapy with a simultaneous integrated boost (uhRT-SIB) in a predominantly palliative cohort. Methods: We retrospectively analysed consecutive patients treated from April 2022 to June 2026, with a data cut-off of 7 July 2026. Image-guided VMAT delivered 33 Gy and 24 Gy to the high- and lower-dose planning target volumes, respectively. Outcomes included the best documented CTCAE-based symptom response, study-defined volumetric response (>30% GTV reduction), freedom from local progression (FFLP), overall survival (OS), and neurological findings in routine clinical records. Results: Forty-four patients with 45 lesions were treated; 29/45 lesions (64.4%) contacted the plexus. The median observed follow-up was 7.8 months (range 0.6–40.6). Symptoms improved by at least one grade in 16/19 evaluable symptomatic patients (84.2%, 95% CI 62.4–94.5%). The median times to first documented benefit and best symptom grade among responders were 9 and 23 days. The first-scan volumetric response occurred in 24/30 evaluable lesions (80.0%, 95% CI 62.7–90.5%). Six- and 12-month FFLP were 84.7% (95% CI 63.9–94.0%) and 73.7% (95% CI 49.7–87.6%), respectively. The median OS was 9.6 months. No clinical diagnosis of radiation-induced brachial plexopathy was documented; neurological assessment was not standardised. Conclusions: In this predominantly palliative cohort, six-fraction uhRT-SIB was associated with symptom improvement in 84.2% of evaluable symptomatic patients, study-defined volumetric response in 80.0% of evaluable lesions, and 12-month FFLP of 73.7%. No clinical diagnosis of radiation-induced brachial plexopathy was documented during routine follow-up, although the assessment of late neurological toxicity was limited.