Comparative Analysis of Photon Stereotactic Radiotherapy and Carbon-Ion Radiotherapy for Elderly Patients with Stage I Non-Small-Cell Lung Cancer: A Multicenter Retrospective Study

SIMPLE SUMMARY: Surgery is the standard treatment for stage I non-small-cell lung cancer (NSCLC), but is often difficult to perform in elderly patients due to their comorbidities and inferior physical status. Stereotactic body radiotherapy (SBRT) is expected to be an alternative treatment and is becoming widely used. Meanwhile, carbon ion radiotherapy (CIRT) is being recognized as an attractive treatment option with potentially lower toxicity for elderly patients with co-morbidities. The aim of this retrospective study was to assess the efficacy and safety of the two modalities for NSCLC in the elderly using Japanese multicenter data. The data on SBRT and single CIRT in consecutive patients ≥80 years of age suggested that the two modalities were comparable in terms of efficacy, at least in Japan during the study period; single CIRT was associated with a lower incidence of severe radiation pneumonitis, indicating a potentially safer treatment. ABSTRACT: The emergence of an aging society and technological advances have made radiotherapy, especially stereotactic body radiotherapy (SBRT), a common alternative to surgery for elderly patients with early stage non-small-cell lung cancer (NSCLC). Carbon-ion radiotherapy (CIRT) is also an attractive treatment option with potentially lower toxicity for elderly patients with comorbidities. We compared the clinical outcomes of the two modalities using Japanese multicenter data. SBRT (n = 420) and single-fraction CIRT (n = 70) data for patients with stage I NSCLC from 20 centers were retrospectively analyzed. Contiguous patients ≥ 80 years of age were enrolled, and overall survival (OS), disease-specific survival (DSS), local control (LC), and adverse event rates were compared. The median age was 83 years in both groups and the median follow-up periods were 28.5 and 42.7 months for SBRT and CIRT, respectively. The 3-year OS, DSS, and LC rates were 76.0% vs. 72.3% (p = 0.21), 87.5% vs. 81.6% (p = 0.46), and 79.2% vs. 78.2% (p = 0.87), respectively, for the SBRT vs. CIRT groups. Regarding toxicity, 2.9% of the SBRT group developed grade ≥ 3 radiation pneumonitis, whereas none of the CIRT group developed grade ≥ 2 radiation pneumonitis. SBRT and CIRT in elderly patients showed similar survival and LC rates, although CIRT was associated with less severe radiation pneumonitis.