Pre-Treatment C-Reactive Protein Predicts Survival in Small Cell Lung Cancer Patients

Abstract

Improved prognostication of small cell lung cancer (SCLC) patients could strengthen the treatment strategy and, thereby, potentially improve the overall survival (OS) of these patients. C-reactive protein (CRP) has been proposed as a prognostic indicator of inferior survival, although so far, only based on data from smaller studies. Data on SCLC patients diagnosed from January 2009 to June 2018 were extracted from the Danish Lung Cancer Registry and the clinical laboratory information system. CRP measurements were divided at the clinical cut-off value of 8 mg/L or 75 nmol/L) and stratified into quartiles. Cox proportional hazards model assessed the prognostic value of the CRP level. C-statistics further evaluated the biomarker’s prognostic value. In total, 923 patients were included. A pre-treatment CRP level above the clinical cut-off significantly correlated to inferior OS (adjusted hazard ratio (HR) = 1.25 (95% confidence interval (CI): 1.08–1.46). When divided into quartiles, a level-dependent correlation was observed with only the highest quartiles significantly associated with OS (3rd quartile: adjusted HR = 1.26 (95% CI: 1.03–1.55) 4th quartile: adjusted HR = 1.44 (95% CI: 1.17–1.77)). Adding CRP level to already well-established prognostic factors improved the prognostication of SCLC patients. In conclusion, high pre-treatment CRP level is an independent prognostic factor in SCLC patients.