Physical Activity and Exercise Interventions in Cancer Survivors

The field of exercise oncology has developed such that it is clear that people affected by cancer should be encouraged to be physically active from the point of diagnosis; indeed, this is now a key component of the survivorship care package in many countries. However, there are still gaps in the evidence. The majority of evidence for the benefits of exercise after cancer comes from breast, prostate, and colorectal cancer patients, usually without metastatic disease. Trials have usually been rated as low to moderate in quality, and although double-blinding will always be an issue in behavioral trials, there is a need to approach exercise studies with the rigor applied to drug trials if it is to be considered an adjuvant cancer therapy. Additionally, there are still gaps around the most appropriate types of exercise for specific cancer sites and how best to implement exercise as part of cancer care, balancing interventions that are likely to reach a large number of patients (e.g., remote, digital) versus those that may have greater benefit (e.g., supervised, face to face). Finally, while observational data are strongly supportive of higher self-reported postdiagnosis physical activity being associated with lower all-cause and cancer-specific mortality, and possibly recurrence, definitive trial data does not yet exist (although a number of trials are underway). Until survival data are generated, caution should be used in how the benefits of exercise are presented to cancer patients, with a focus on the large number of outcomes that have been robustly demonstrated to improve in response to intervention.