This study reported outcomes of 25 patients with limited-stage small cell lung cancer treated with combined proton and carbon-ion radiotherapy. Proton and sequential carbon-ion radiation were delivered with a median dose of 67.1 GyE as fraction doses of 2.0-2.2 GyE with proton beams in 20-23 fractions and 3.0-3.8 GyE with carbon ions in 5-8 fractions, with concurrent chemotherapy for all patients. The 2-year overall and locoregional progression-free survival rates were 81.7% and 66.7%, respectively. Grade 1, 2, and 3 acute toxicities occurring in 12.0%, 68.0%, and 20.0% of patients, respectively. All grade 3 acute toxicities were related to haematological alterations, except for one patient who experienced grade 3 acute radiation esophagitis during PRT, and another who experienced a grade 3 bronchial obstruction accompanied by obstructive atelectasis as a late adverse effect. The authors concluded that proton plus carbon-ion radiotherapy using pencil beam scanning yielded promising survival rates and tolerability in patients with limited-stage small cell lung cancer.