Long-term outcomes of high-dose carbon-ion radiotherapy for central non-small cell lung cancer: a single-centre, retrospective study

Background The feasibility and efficacy of radiation therapy (RT) for central non-small cell lung cancer (NSCLC) remain controversial owing to the increased risk of severe adverse events (AEs), including pneumonia, perforation of mediastinal organs (esophagus and trachea), and bleeding. Carbon-ion radiation therapy (CIRT) is an effective RT modality owing to its steep dose distribution and high biological efficacy. We retrospectively analyzed the clinical course of central NSCLC treated using CIRT. Methods Thirty patients who received CIRT with 68.4 Gy (RBE) in 12 fractions for pathologically proven central NSCLC between 2006 and 2018 were reviewed. The clinical stage was re-evaluated according to the UICC 8th edition, and adverse events were evaluated using CTCAE ver.5.0. The Kaplan–Meier method was used to evaluate overall survival (OS), disease-specific survival (DSS), and local control (LC). Results The median age was 75 years (range 55–85). All patients had concomitant chronic obstructive pulmonary disease (COPD), and 20 (67%) were regarded as inoperable. At a median follow-up of 63 months in surviving patients, 14 patients died, but no treatment-related deaths were observed. The 3-year OS, DSS, and LC rates were 72.4, 75.8, and 88.7%, respectively. Two patients experienced grade 3 pneumonitis, representing 6.7% of the cohort, but no grade ≥ 3 AEs involving the mediastinal organs occurred. Conclusions CIRT using our dose fractionation is feasible and effective for central NSCLC and may be a secure treatment option for patients with central NSCLC who are unmet for other curative treatments.