Objective:

To evaluate the predictive value of Ki-67 expression for pathological response (MPR/pCR) in patients with resectable lung squamous cell carcinoma receiving neoadjuvant immunotherapy plus chemotherapy.

Approach:

• Study Design: Retrospective analysis of 137 patients with stage IIIA–IIIB lung SCC who received neoadjuvant PD-1 inhibitors plus platinum-based chemotherapy followed by surgery.
• Assessment Methods: Major pathological response (MPR) and pathological complete response (pCR) were assessed per IASLC criteria. Ki-67 expression was measured by immunohistochemistry.
• Statistical Analysis: ROC curve, univariate and multivariate logistic regression were used to evaluate predictive performance.

Key Findings:

• MPR/pCR was achieved in 77/137 patients (56.2%).
• The optimal Ki-67 cutoff was 55% (AUC = 0.785, 95%CI: 0.707–0.862, P<0.001).
• High Ki-67 (≥55%) was associated with a significantly higher MPR/pCR rate than low Ki-67 (69.6% vs. 27.9%, P<0.001).
• Ki-67 expression and smoking status were independent predictors of MPR/pCR.

Interpretation:

Pretreatment Ki-67 expression at an optimal cutoff of 55% is a robust independent predictor of pathological response to neoadjuvant chemoimmunotherapy in locally advanced lung SCC.

Limitations:

• The study is retrospective and conducted at a single center.
• Prospective multi-center validation is required before routine clinical application.

Conclusion:

Ki-67 assessment may help identify patients likely to benefit from neoadjuvant therapy.