Analysis of the relationship between Ki-67 expression and chemotherapy and prognosis in advanced non-small cell lung cancer

Background: To analyse the relationship between the Ki-67 index of advanced non-small cell lung cancer (NSCLC) and the objective response rate (ORR) and progression-free survival (PFS) of patients who received chemotherapy. Methods: The Ki-67 index of advanced NSCLC pathology was established by immunohistochemistry; using univariate and multivariate analyses, we retrospectively analysed the relationship between the Ki-67 index of 112 advanced NSCLC patients in our hospital and chemotherapy response and PFS. Both epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) were found to be wild type in adenocarcinoma patients, and no gene testing was performed for those with squamous cell carcinoma. All selected patients received four cycles of platinum-based chemotherapy, and according to the Response Evaluation Criteria in Solid Tumors (RECIST, version 1.1), the curative effect was evaluated after every two cycles. Results: In the univariate and multivariate analyses, the Ki-67 index was significantly associated with the objective response to chemotherapy (B =- 0.069, P=0.000). Ki-67 expression could also accurately predict the ORR of chemotherapy [P<0.0001, area under the curve (AUC) =0.7467, 95% confidence interval (CI): 0.6578-0.8356]: squamous cell carcinoma group [P= 0.0003, AUC =0.8065 (95% CI: 0.6922-0.9208)], adenocarcinoma group [P=0.0193, AUC =0.6810 (95% CI: 0.5360-0.8262)]. The overexpression of Ki-67 was a negative prognostic factor for PFS in advanced NSCLC (P<0.0001): squamous cell carcinoma (P=0.0055), adenocarcinoma (P<0.0001). According to the multivariate Cox analysis, Ki-67 index (P=0.000) and stage (P=0.001) were negative factors of PFS. Conclusions: The Ki-67 index might be a clinically significant biomarker in advanced NSCLC and may be able to predict the efficacy of chemotherapy. High expression of Ki-67 might also be an indicator of shortened PFS time.