Cancer risk by combined levels of YKL-40 and C-reactive protein in the general population

BACKGROUND: YKL-40 and C-reactive protein (CRP) are biomarkers that may reflect cancer-related subclinical inflammation. We assessed elevated YKL-40 and CRP levels as combined risk predictors for cancer. METHODS: We measured plasma YKL-40 and CRP at baseline in 8706 individuals from the Danish general population. RESULTS: Hazard ratio (HR) of gastrointestinal cancer for a doubling of YKL-40 levels was 1.37 (95% CI: 1.17-1.61) and indifferent to adjustment for CRP levels. Hazard ratio of lung cancer for a doubling of CRP levels was 1.35 (1.17-1.56) and indifferent to adjustment for YKL-40 levels. Compared to individuals with both low CRP (<1.7 mg l(-1)) and YKL-40 (<154 μg l(-1)), individuals with high YKL-40 but low CRP had an HR of gastrointestinal cancer of 3.36 (1.70-6.64), whereas individuals with high CRP but low YKL-40 had an HR of lung cancer of 2.19 (1.24-3.87). The area under the receiver operating characteristic (ROC) curve was 0.68 for the ability of YKL-40 to predict gastrointestinal cancer and 0.67 for the ability of CRP to predict lung cancer. CONCLUSION: Elevated YKL-40 levels are associated with increased risk of gastrointestinal cancer, independently of CRP levels, whereas elevated CRP levels are associated with increased risk of lung cancer, independently of YKL-40 levels.