Prognostic Significance of C-PLAN Index in Patients Treated with Immunotherapy for Non-Small-Cell Lung Cancer

Background/Objectives: Non-small-cell lung cancer (NSCLC) is a common disease with a high mortality rate and is often treated with immunotherapies; however, prognostic markers are required to identify patients who are most likely to benefit from these treatments. Therefore, we designed this study to assess the prognostic significance of the C-PLAN index, which includes performance status (PS) and C-reactive protein (CRP). Methods: A total of 560 patients were included in this multicenter study. Patients had been diagnosed with NSCLC and had received nivolumab therapy. The C-PLAN index, defined in 2022, is a score derived from the combination of PS, CRP, lactate dehydrogenase (LDH), albumin, and neutrophil–lymphocyte ratio (NLR). Patients were classified into good-, moderate-, and poor-prognosis groups according to the C-PLAN score. Results: The median metastatic overall survival was 25 months in the group with a C-PLAN score < 2 and 6 months in the group with a C-PLAN score ≥ 2 (p < 0.001). The median metastatic progression-free survival was 11 months in the group with a C-PLAN score < 2 and 3 months in the group with a C-PLAN score ≥ 2. Conclusion: This is the first comprehensive study demonstrating that the C-PLAN index can be used for prognostic purposes in immunotherapy. This score, which can be easily, economically, and practically calculated in outpatient clinics, can predict patient prognosis and determine who should receive longer durations of immunotherapy.