C‐PLAN index as a prognostic factor for patients with previously untreated advanced non‐small cell lung cancer who received combination immunotherapy: A multicenter retrospective study

BACKGROUND: Combination immunotherapy (immune checkpoint inhibitors and cytotoxic anticancer agents) is widely used as first‐line treatment for advanced non‐small cell lung cancer (NSCLC). However, the therapeutic effect of combination immunotherapy has not been fully investigated. C‐reactive protein, performance status, lactate dehydrogenase, albumin, and derived neutrophil‐to‐lymphocyte ratio (C‐PLAN) are useful biomarkers for predicting the prognosis of NSCLC; however, there are no reports examining the C‐PLAN index, which combines these five factors in a single prognostic factor. METHODS: We retrospectively collected data from 178 patients with previously untreated advanced NSCLC who received combination immunotherapy at multicenter institutions in Nagano Prefecture between December 2018 and April 2022. We investigated the utility of the C‐PLAN index as a prognostic factor using Cox regression analysis and correlated it with survival. RESULTS: The good and poor C‐PLAN index groups included 85 and 93 patients, respectively. The good C‐PLAN index group had a longer median progression‐free survival (PFS) (10.7 vs. 6.0 months; p = 0.022) and overall survival (OS) (25.3 vs. 16.5 months; p = 0.003) than the poor C‐PLAN index group. The C‐PLAN index was an independent favorable prognostic factor that correlated with PFS and OS in multivariate analysis. The good C‐PLAN index group had a higher proportion of never‐smokers (16.5 vs. 4.3%; p = 0.007) and stage III disease/postoperative recurrence (32.9 vs. 15.1%; p = 0.005) than the poor C‐PLAN index group. CONCLUSION: The C‐PLAN index is a useful prognostic factor for patients with previously untreated advanced NSCLC undergoing combination immunotherapy.