Cardiorespiratory fitness, C-reactive protein and lung cancer risk: A prospective population-based cohort study.

Background: Little is known about the joint impact of C-reactive protein (CRP) and cardiorespiratory fitness (CRF) in lung cancer risk. The aim of this study is to examine the joint impact of CRF and CRP in predicting lung cancer risk.
Methods: A population-based cohort study of 2276 men with no history of cancer was carried out. Baseline measures of CRP and CRF were divided into median values and categorised. During an average follow-up of 21-years, 73 cases of lung cancer occurred.
Results: In a multivariate model, men with the combination of high CRP (>50% 1.24 mg/l) and low CRF (maximal oxygen uptake (VO2max) < 50% 30.08 ml/kg/min) had a fourfold (relative risk (RR) 4.19 95% confidence interval (CI) 1.66-10.57, p < 0.01) risk of lung cancer as compared to the reference group of low CRP (<50% 1.24 mg/l) and high CRF (VO2max>50% 30.08 ml/kg/min). Furthermore, men categorised in high CRP and combined with either low/high CRF, had an increased risk for lung cancer as compared to reference group. In further separate independent analysis for CRP and CRF, lung cancer risk was threefold for high CRP (RR 3.22, 95% CI 1.44-7.20, p < 0.01) and low CRF (RR 3.15, 95% CI 1.27-7.78, p = 0.01) as compared to reference CRP (>2.38 mg/l) and CRF (>35.15 ml/kg/min).
Conclusions: In this study, the joint impact of CRP and CRF is a strong risk marker for lung cancer. Furthermore, men with an increase in CRP were at higher risk for lung cancer than men with low CRP and high CRF may reduce the risk.
(Copyright © 2015 Elsevier Ltd. All rights reserved.)