KEY POINTS
- This single-institution retrospective cohort included 44 patients with 45 tumors adjacent to or involving the brachial plexus; 90.9% of treated lesions were metastatic, most commonly from lung or breast cancer.
- All lesions received image-guided VMAT with a simultaneous integrated boost: 33 Gy in 6 fractions to gross/high-risk disease and 24 Gy in 6 fractions to a larger lower-dose PTV, generally completed in 7 days.
- Direct tumor–plexus contact was present in 29/45 lesions (64.4%). Median brachial plexus D0.03cc was 32.4 Gy, reaching a maximum of 34.5 Gy, despite substantial tumor proximity or encasement.
- Among 19 evaluable patients with baseline plexus-related symptoms, 16/19 (84.2%) improved by at least one CTCAE grade. The median time to first documented benefit among responders was only 9 days, and 9 patients achieved complete symptom resolution.
- At the first evaluable post-treatment CT, 24/30 lesions (80.0%) met the study-defined volumetric-response threshold of >30% reduction, with a median GTV reduction of 70.1%. Using a stricter RECIST-inspired volumetric definition, response was 60%.
- Freedom from local progression among lesions with imaging follow-up was 84.7% at 6 months and 73.7% at 12 months. Median overall survival was 9.6 months, consistent with the predominantly palliative population.
- No clinical diagnosis of radiation-induced brachial plexopathy was recorded. This should not be interpreted as proof of safety: neurological follow-up was symptom-driven rather than standardized, median observed follow-up was short, and only 16 patients remained under observation for at least 12 months.
- Response estimates are susceptible to selection bias because only 31/45 lesions had post-treatment imaging; patients with imaging survived substantially longer than those without it. Concurrent systemic therapy and changes in analgesics also prevent causal attribution of symptom improvement to RT alone.
CLINICAL TAKEAWAY
For patients with limited life expectancy and symptomatic tumors involving the brachial plexus, a six-fraction course may offer rapid palliation with meaningful local control while limiting treatment visits. The regimen should not be interpreted as establishing a new brachial plexus tolerance threshold, because late neurological toxicity was not assessed systematically.