Elevated baseline C-reactive protein predicts poorer survival in lung cancer: a 22-year retrospective cohort study

Background: Systemic inflammation has been implicated in cancer progression and C-reactive protein (CRP) is an established inflammatory biomarker. We investigated clinical and pathological factors associated with elevated baseline CRP in lung cancer and evaluated their relationships with survival outcomes. Methods: We retrospectively reviewed 1,339 patients with newly diagnosed lung cancer at Peking Union Medical College Hospital (PUMCH) between October 2000 and March 2022. Baseline serum CRP was measured prior to anti-tumor therapy; CRP ≥10 mg/L was defined as elevated. Patient demographics, tumor characteristics and treatment variables were compared by CRP level. Overall survival (OS) and progression-free survival (PFS) were assessed using Kaplan-Meier analysis with log-rank tests. Cox proportional hazards models were used to identify independent prognostic factors for OS and PFS. The study was approved by the ethical review committee of PUMCH. Results: Elevated CRP (≥10 mg/L) was present in 41.0% of patients at diagnosis. High CRP was significantly associated with adverse clinical features, including older age, male sex, smoking, alcohol use, advanced stage III–IV disease, Eastern Cooperative Oncology Group (ECOG) performance status score 2–4, absence of driver gene mutations, positive programmed death ligand 1 (PD-L1) expression, presence of metastases and receipt of immunotherapy. In Kaplan-Meier analyses, patients with high CRP had significantly shorter OS and PFS than those with CRP