Real-world clinical outcomes of concurrent chemotherapy and dose-escalated twice-daily radiotherapy with Simultaneous Integrated Boost (SIB) for limited-stage small cell lung cancer

Abstract

This retrospective study evaluated real-world outcomes of dose-escalated twice-daily radiotherapy with simultaneous integrated boost in limited-stage small cell lung cancer. Sixty-six patients received concurrent chemoradiotherapy. Median overall survival was 53 months, with acceptable toxicity. Local control was favorable, though distant metastases remained common. Performance status and treatment volume were significant prognostic factors, supporting the feasibility and effectiveness of this approach. Introduction: The standard concurrent chemoradiotherapy (c-CT) regimen for limited-stage small cell lung cancer (LS-SCLC) has historically been 45 Gy in 30 twice-daily (BID) fractions. Recent findings by Yu et al. suggest that dose escalation up to 54 Gy may improve overall survival (OS) without increasing toxicity. However, real-world evidence on the safety and efficacy of dose escalation using modern radiotherapy techniques remains limited. This study aimed to evaluate survival outcomes and treatment tolerability in LS-SCLC patients treated with dose-escalated BID radiotherapy using the simultaneous integrated boost (SIB) technique. Materials and Methods: Patients with LS-SCLC who received c-CT and BID radiotherapy with SIB-based dose escalation (54Gy/30fr) were retrospectively analyzed. All treatment planning was performed with Intensity-Modulated Radition Therapy using heterogeneity correction after 4D-CT simulation. The primary endpoint was OS; secondary endpoints included disease-free survival (DFS) and treatment-related toxicities. Results: From March 2010 to December 2024, 66 patients were included. Median age was 65 years, with a median follow-up of 31 months. Median OS was 53 months and median DFS 18 months. Grade 3 acute esophagitis occurred in 7.6%, and grade 3 pneumonitis in 3%. No grade >4 toxicities were observed. No grade >4 toxicities were reported. Conclusion: Dose-escalated BID radiotherapy using SIB was effective and well tolerated, yielding favorable local control. However, distant metastases remained the predominant failure pattern, limiting the OS benefit compared with the 62.4 months reported by Yu et al. Interpretation should consider the retrospective design, treatment heterogeneity over a decade, and potential selection biases.