Estimated cardiorespiratory fitness in relation to overall, breast and prostate cancer incidence: the Norwegian HUNT study

Abstract

To investigate the relationships between estimated cardiorespiratory fitness (eCRF) and the incidence of overall, breast, and prostate cancer in a large prospective cohort study. We included 46,968 cancer-free adults who participated in the second survey of the Trøndelag Health Study in Norway. Sex-specific non-exercise algorithms were used to estimate CRF. eCRF was classified into sex and age-specific tertiles, that is, into low, medium and high levels. Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). Over a median of 22.1 years' follow-up, there were 7752 overall, 858 breast and 1376 prostate cancer cases. Medium and high levels of eCRF were associated with a reduced incidence of overall cancer in a dose-response manner in all participants (HR 0.96, 95% CI 0.90 to 1.01 and HR 0.85, 95% CI 0.79 to 0.91, respectively, and p-value for trend <0.001). No association was observed between eCRF and breast cancer incidence in women. Only the high level of eCRF seemed to be associated with a reduced incidence of prostate cancer in men (HR 0.85, 95% CI 0.72 to 1.02). eCRF may be a practical and cost-effective means of investigating the association between CRF and cancer incidence.