Cardiorespiratory Fitness and All-cause Mortality in Cancer Survivors

Background: The association between cardiorespiratory fitness (CRF) and all-cause mortality in cancer survivors is understudied.

Methods: Participants comprised 2,891 men and women aged ≥20 years (mean age 53) with a medical diagnosis of cancer and who had a medical examination during 1987-2003 in the Aerobics Center Longitudinal Study.  They were free of cardiovascular disease (CVD) and achieved ≥85% of their age-predicted maximal heart rate on a treadmill exercise test at baseline.  CRF was estimated from a maximal treadmill test and categorized into ‘low’, ‘middle’, and ‘high’ based on the tertiles of age- and sex-specific treadmill time in this population.  Mortality follow-up was through 2003 using the National Death Index.

Results: During an average follow-up of 7.1 years, 89 deaths from any cause occurred (45 died by cancer, 25 by CVD, and 19 from other causes).  The hazard ratios and 95% confidence intervals for all-cause mortality were 0.61 (0.36-1.02), and 0.56 (0.32-0.98) in middle and high CRF categories, respectively, compared with the low CRF category after adjusting for age, sex, examination year, smoking status, alcohol intake, body mass index (BMI), and medical conditions (abnormal electrocardiogram, hypertension, diabetes, and hypercholesterolemia)(p for trend=0.039).  The association remained significant after excluding deaths within the first year of follow-up.  The inverse association between CRF and mortality was significant in normal weight individuals (p for trend <0.05), but not in overweight/obese individuals (p for trend >0.05).

Discussion: This study shows an inverse association between fitness and risk of death in cancer survivors.