Association of post-diagnosis cardiorespiratory fitness with cause-specific mortality in cancer

Abstract

Abstract Aims  The prognostic importance of post-diagnosis assessment of cardiorespiratory fitness (CRF) in cancer patients is not well established. We sought to examine the association between CRF and mortality in cancer patients. Methods and results  This was a single-centre cohort analysis of 1632 patients (58% male; 64 ± 12 years) with adult-onset cancer who were clinically referred for exercise treadmill testing a median of 7 [interquartile range (IQR): 3–12] years after primary diagnosis. Cardiorespiratory fitness was defined as peak metabolic equivalents (METs) achieved during standard Bruce protocol and categorized by tertiles. The association between CRF and all-cause and cause-specific mortality was assessed using multivariable Cox proportional hazard models adjusting for important covariates. Median follow-up was 4.6 (IQR: 2.6–7.0) years; a total of 411 deaths (229, 50, and 132 all-cause, cardiovascular (CV), and cancer related, respectively) occurred during this period. Compared with low CRF (range: 1.9–7.6 METs), the adjusted hazard ratio (HR) for all-cause mortality was 0.38 [95% confidence interval (CI): 0.28–0.52] for intermediate CRF (range: 7.7–10.6 METs) and 0.17 (95% CI: 0.11–0.27) for high CRF (range: 10.7–22.0 METs). The corresponding HRs were 0.40 (95% CI: 0.19–0.86) and 0.41 (95% CI: 0.16–1.05) for CV mortality and 0.40 (95% CI: 0.26–0.60) and 0.16 (95% CI: 0.09–0.28) for cancer mortality, respectively. The adjusted risk of all-cause, CV, and cancer mortality decreased by 26%, 14%, and 25%, respectively with each one MET increment in CRF. Conclusion  Cardiorespiratory fitness is a strong, independent predictor of all-cause, CV, and cancer mortality, even after adjustment for important clinical covariates in patients with certain cancers.