Association between C-reactive protein variability and cancer incidence: a longitudinal prospective cohort study

Background The association between inflammation and cancer has been widely studied, but research on the relationship between the magnitude of inflammatory fluctuations and cancer remains limited. Therefore, this study aims to investigate the association between C-reactive protein (CRP) variability and the occurrence of cancer. Methods A total of 42,514 participants were included, and their CRP levels were measured over a 4-year period. We used the coefficient of variation (CV) of CRP to quantify the variability in inflammation. Cox regression analysis was used to assess the association between CRP variability and cancer risk after adjusting for potential confounding factors. Results High CV of CRP significantly associated with reduced cancer risk (hazard ratio (HR) = 0.84; 95% CI: 0.75–0.94, P  = 0.003). Participants with high CRP and low CV had a significantly increased risk of cancer (HR = 1.42; 95% CI: 1.18–1.70, P  < 0.001). In the population with long-term stable CRP levels, there is a significant association between the CV and the risk of cancer (HR = 0.81; 95% CI: 0.72–0.92, P  = 0.001). Furthermore, the association between the CV and lung cancer was most pronounced. Sensitivity analyses confirmed the stability of the association between CRP variability and cancer. Conclusion High CRP variability is significantly associated with reduced risk of cancer, particularly in the case of lung cancer. This provides a new perspective and evidence for exploring the relationship between inflammation and cancer.