KEY POINTS
- This retrospective cohort included 39 patients with limited-stage SCLC treated with carbon-ion RT between 2020 and 2026. Most had advanced nodal disease: 82.1% were N2–N3, and 71.7% had stage IIIB–IIIC disease.
- Treatment used a simultaneous integrated strategy over only 12 fractions. Elective lymphatic regions received 48 Gy(RBE), while gross primary and nodal disease received a cumulative 72 Gy(RBE).
- Platinum-etoposide chemotherapy was integrated into treatment: 65.8% received concurrent chemoradiotherapy, 34.2% sequential chemotherapy, and 59% also received immunotherapy, creating substantial treatment heterogeneity.
- At three months, objective response was 64.1%. Both 1- and 2-year local control were 91.2%, while 2-year progression-free survival was 47.8% and median PFS was 24 months.
- Overall survival was 91.7% at 1 year and 62.5% at 2 years, with a reported median OS of 44 months. These outcomes cannot be directly compared with historical photon cohorts because there was no contemporaneous control arm.
- Acute radiation-associated injury consisted primarily of esophagitis, pneumonitis and one case of pharyngeal edema. No grade ≥3 acute radiation-related toxicity was reported; grade 3–4 myelosuppression occurred but was predominantly attributed to chemotherapy.
- Late radiation toxicity was not systematically captured. The cohort was small, single-centre and retrospective, several patients received immunotherapy, and 13 patients exceeded the recommended affected-lung V20 limit, making both efficacy and safety conclusions preliminary.
CLINICAL TAKEAWAY
A 12-fraction carbon-ion strategy achieved impressive local control with limited acute thoracic toxicity in this small LS-SCLC cohort. The result is hypothesis-generating rather than comparative evidence: without a photon control group and with no standardized late-toxicity data, carbon ions cannot yet be considered superior to contemporary chemoradiotherapy.