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

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.

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.

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 <10 mg/L (median OS 19.0 vs. 44.0 months; 5-year OS 15.8% vs. 37.2%; median PFS 8.0 vs. 12.0 months; 2-year PFS 12.2% vs. 23.1%, respectively; log-rank P<0.001 for both). In multivariate Cox analysis adjusting for age, sex, smoking, comorbidities, histology, stage, performance status and metastasis, baseline CRP ≥10 mg/L remained an independent predictor of worse OS and PFS.

Baseline CRP elevation in lung cancer correlates with more aggressive disease characteristics and independently portends inferior survival. CRP, as an inexpensive routine test, could aid in risk stratification and prognostication. Integrating CRP into clinical decision-making may improve identification of high-risk patients who might benefit from intensified or alternative therapeutic strategies.