Research in people without cancer demonstrates substantial inter-individual heterogeneity in response to exercise. Cancer introduces additional factors that may further influence the response. It is unclear which cancer patients do and don’t respond to exercise or what factors influence the magnitude of response. The aim of this study was to explore whether there is heterogeneity of effect among people with cancer in response to exercise.
600 people with cancer (70% female; age 61±12 years; BMI:27±5kg.m-2; 2.1±3.2years since diagnosis) within 2-years of treatment participated in this investigation. Participants had been diagnosed with one of ~40 different types of cancer, predominately breast (43%), prostate (13%) and bowel (9%). Participants self-enrolled in a 3-month community-based exercise program involving supervised moderate-intensity aerobic and resistance exercise. Assessment of physical function, fatigue, distress and quality of life (QOL) were conducted at baseline and post-intervention.
Significant (p≤0.05) differences existed in the magnitude of change in all variables assessed between non-responders(quartile 1), low-responders(quartile 2), moderate-responders(quartile 3) and high responders(quartile 4). Changes in physical function (V02Peak mean change:1.4±2.3mL/kg/min; high-responders:4.3±1.8mL/kg/min; non-responders:-1.1±1.6mL/kg/min), fatigue (FACIT-Fatigue mean change:2.9±8.3; high-responders:14.2±5.8; non-responders:-6.0±4.0), distress (BSI-18 mean change:-1.3±5.4; high-responders:-7.2±4.2; non-responders:5.4±4.4) and QOL (SF-36 physical composite mean change:2.5±6.4; high-responders:10.9±3.8; non-responders:-5.1±3.5) varied significantly. Higher attendance was associated with greater change in function but not fatigue, distress or QOL. Patients with poorest baseline values had significantly greater change in all variables. The magnitude of change did not vary between patients currently on- versus off-treatment, <1-year versus >1-year since diagnosis or common versus rare cancer types.
Significant individual variability exists in the response to exercise among people with cancer. The greatest improvement in symptom severity and QOL is among patients with the worst symptoms. Thus, people with cancer who may be least likely to be referred to an exercise program are the patients who benefit the most.