Outcome analysis and associations with Charlson comorbidity index in the early-stage lung cancer patients treated with stereotactic radiotherapy

Abstract Background Lung stereotactic body radiotherapy (SBRT) is the standard of care for patients with inoperable early-stage non-small cell lung cancer (NSCLC), who frequently have significant comorbidities. There is no standardised method to predict how age and comorbidities influence SBRT efficacy or toxicity. The Charlson Comorbidity Index (CCI) and its age-adjusted variant (aCCI) have been proposed as prognostic tools, though their predictive value remains uncertain. This study assessed the prognostic relevance of the CCI and aCCI in patients undergoing SBRT for early-stage NSCLC. Methods This retrospective single-institution study included patients with NSCLC treated with SBRT between January 2010 and December 2023. Patients receiving standard SBRT dose-fractionation for peripheral, central, and ultracentral tumours were eligible. CCI and aCCI scores were calculated for all patients. The primary objective was to compare overall survival (OS) between patients with low (< 2) and high (≥ 2) CCI scores. Secondary outcomes included associations of CCI and aCCI with OS, cancer-specific survival (CSS), local failure (LF), regional failure (RF), distant failure (DF), and treatment-related toxicity. Cox proportional hazards regression was used. Results A total of 170 patients were included, with a median age of 77 years (range: 51–93). After a median follow-up of 36.4 months, 68 deaths occurred, including 24 cancer-specific deaths. Median OS was 59.4 months (95% CI: 49.9–104.1), while median CSS was not reached. High CCI (> 2) was not associated with worse OS (univariate: HR 0.97, 95% CI: 0.43–2.16, p = 0.93; multivariate: HR 0.16, 95% CI: 0.03–0.92, p = 0.04). High aCCI (> 6) was also not significantly associated with OS (HR 1.02, 95% CI: 0.43–2.38, p = 0.97). Patients with peripheral tumours had a significantly higher risk of death than those with central tumours (HR 4.7 × 10⁹, 95% CI: 1.1 × 10⁹–2.01 × 10¹⁰, p < 0.001). No other variables significantly influenced survival. SBRT was well tolerated, with no grade 4–5 toxicities or treatment-related deaths. Conclusions The CCI and aCCI did not predict overall or disease-specific survival in patients treated with SBRT for early-stage NSCLC. These findings suggest that current comorbidity indices may be inadequate in this population and highlight the need for improved prognostic tools to guide treatment decisions.