Cancer-Related Fatigue Is Associated With Objective Measures of Physical Function Before and After a Clinical Exercise Program: A Retrospective Analysis

Background: Cancer-related fatigue (CRF) is a common symptom reported by survivors of cancer. CRF is associated with reduced self-reported physical function, but associations with objective measures of physical function are less robust. Exercise programs have been shown to improve both CRF and objective physical function, but the interaction of exercise, CRF, and function has not been explored.Methods: Retrospective data were collected from baseline (n = 420) and final assessments (n = 234) of survivors who participated in a 3-month clinical exercise program. Assessments included measures of CRF (Functional Assessment of Chronic Illness Therapy-Fatigue) and physical function (6-minute walk test, usual and fast gait speed, 30-second sit-to-stand test, and the Timed Up and Go test). Multiple regression analyses investigated associations between CRF and physical function before and after the program. CRF and functional changes following the program were calculated and associations investigated with multiple regressions.Results: All measures of CRF and physical function significantly improved following the program (P < .01). CRF was associated with all functional measures at baseline (standardized beta = -0.18 to 0.29, P < .01) and final assessments (r = -0.27 to 0.26, P < .01). Changes in CRF were associated with changes in function (standardized beta = -0.12 to 0.23, P < .05), except usual gait speed (P = .17).Conclusion: This investigation demonstrated associations between CRF and objective physical function before and after participation in an exercise program. The 3-way interaction between CRF, physical function, and exercise can be used clinically to personalize rehabilitation strategies. Future studies should investigate changes in CRF and function during an exercise program.