KEY POINTS
- This retrospective referral-center study included 46 adults treated with high-dose carbon ion re-irradiation for locoregional recurrent pelvic sarcoma at CNAO between 2013 and 2023.
- The cohort was dominated by chordoma (80.4%), followed by high-grade chondrosarcoma (13%); recurrences were in-field in 24 patients, marginal in 17, and out-of-field in 5.
- Median prescribed re-irradiation dose was 60 GyRBE; the median cumulative EQD2 D95 to the CTV was 130 Gy, and maximum cumulative EQD2 D1 to the target reached 284 Gy.
- With median follow-up of 32.5 months, 1-, 2-, and 3-year locoregional progression-free survival were 79.1%, 43.9%, and 25.1%; 1-, 2-, and 3-year overall survival were 100%, 93.9%, and 83.1%.
- Grade 3 toxicity at last follow-up included neuropathy in 6.5%, anorectal dysfunction in 8.7%, and skin toxicity in 6.5%; no grade 4 toxicity was reported.
CLINICAL TAKEAWAY
High-dose carbon ion re-irradiation may be a feasible salvage option for carefully selected patients with recurrent pelvic sarcoma, especially chordoma-dominant cases managed in specialist particle therapy centers. The main strength is clinically meaningful follow-up in a rare, difficult re-irradiation setting; the main limitation is the retrospective, single-center design with small numbers, histologic heterogeneity, and no comparator. This is useful evidence worth attention, not a broadly generalizable standard.