Retrospective Analysis of the Timing of Radiotherapy Intervention After Induction Chemoimmunotherapy in Unresectable Locally Advanced Lung Squamous Cell Carcinoma.

BACKGROUND

The optimal combination of immune checkpoint inhibitors (ICIs), radiotherapy, and chemotherapy for unresectable locally advanced lung squamous cell carcinoma (LA-LUSC) remains undefined. This study evaluated induction chemoimmunotherapy followed by radiotherapy ± consolidation ICI in unresectable LA-LUSC, specifically exploring radiotherapy timing impact.

METHODS

We retrospectively analyzed 54 unresectable LA-LUSC patients receiving induction chemoimmunotherapy followed by radiotherapy. Patients were grouped by radiotherapy timing: Early (after 2-3 induction cycles, n = 18) and Late (after 4-6 cycles, n = 36). Survival analysis (Kaplan-Meier, Log-rank) compared progression-free survival (PFS), local PFS (LPFS), distant metastasis-free survival (DMFS), overall survival (OS), and safety. Prognostic factors for PFS/OS were explored.

RESULTS

Median follow-up was 30.7 months. Median PFS for all patients was 21.9 months. Early radiotherapy improved PFS (HR = 0.43, p = 0.024) and LPFS (HR = 0.36, p = 0.038). Radiotherapy after 2-3 induction cycles was an independent predictor of improved PFS (p = 0.040). Overall treatment tolerance was good; grade ≥3 pneumonitis incidence was 5.56%. After propensity score matching, OS was significantly longer in patients receiving induction plus consolidation ICI versus induction ICI alone (HR = 0.51, p = 0.038).

CONCLUSION

Induction chemoimmunotherapy followed by radiotherapy demonstrates promising efficacy and manageable toxicity in unresectable LA-LUSC. Initiating radiotherapy earlier (after 2-3 induction cycles) improves PFS and LPFS and is an independent favorable prognostic factor. Consolidation ICI after combined chemoimmunotherapy and radiotherapy further extends OS compared to induction ICI alone.