Higher Fitness is Associated with Improved Survival among Cancer Patients

Background: Data on the association of cardiorespiratory fitness (CRF) with survival following a diagnosis of cancer is limited. The current analysis evaluated this association in a large cohort of asymptomatic adults.

Methods: We evaluated asymptomatic self-referred adults aged 40-79 years who were screened annually at a tertiary medical center. All subjects were free of cardiovascular disease and cancer at baseline and completed maximal exercise stress test according to the Bruce protocol. Fitness was categorized into age- and sex-specific quintiles (Q) according to Bruce protocol treadmill time with Q1-Q2 defined as low fitness and Q3-Q5 as higher fitness. Cancer data was available from a national cancer registry. The primary end point was all-cause mortality.

Results: Final study population in included 15,849 subjects. Mean age was 51±8 years and 72% were men. During median follow up of 12 years (IQR 6-16) 1,368 (9%) subjects developed cancer and 529 (3%) died. Univariate Cox regression with cancer as a time dependent covariate showed that subjects who developed cancer during follow up were 21 times more likely to die (95% CI 18-25, p<.001). Kaplan Meier analysis showed that the cumulative probability of death from the time of cancer diagnosis was significantly lower among high fitness patients (33% ± 3% vs. 26% ± 2%, p Log rank =.007; Figure 1). Multivariate interaction analysis with cancer as a time dependent covariate showed that cancer-related risk was fitness-dependent, such that in the lower fitness group cancer was associated with 20 folds increased risk of death (95% CI 15.2-25.5) whereas among high fitness group the risk of death was lower (HR=15; 95% CI 11.5-19.8; p for interaction = .085).

Conclusions: Low CRF is associated with worse survival among subjects diagnosed as having cancer during follow up. These findings support the effectiveness of fitness assessment in preventive health care settings.