Promoting exercise after a cancer diagnosis: easier said than done

There is a clear need to better understand the risks associated with the development and progression of cancer in order to design effective primary and secondary prevention strategies. However, it is important to remember that we have solid evidence supporting the putative relationship between certain common behaviours or conditions with risk, and therefore, specific interventions that modify these behaviours/conditions could be helpful. Certainly tobacco control represents a partial victory in the area of behavioural modification to lower the risk of many pathological conditions, including several types of cancer, and vaccines and medications can also prevent cancer but these rely on a traditional medical treatment-based approach. A closely related area focuses on other (non-tobacco) modifiable risk factors for the prevention of recurrence in curatively treated malignancies. In that regard, emerging evidence indicates that regular aerobic (endurance) exercise is associated with significant reductions in recurrence and cancer-specific mortality in patients with early breast, prostate, and colorectal cancers ( Betof et al, 2013 ). If real, this suggests that there are a far greater number of factors that can influence tumour progression than just the genomic abnormalities, the major focus of current oncology research efforts. This means that research must also extend to the ‘soil’ (as opposed to the ‘seed’) in terms of metastasis and disease progression. That one intervention could potentially benefit so many different solid tumours suggests an overall pathophysiological effect on the host and multiple organ systems with nearly universal interactions despite the evidence that many cancers have diverse causation and molecular biology. Although scientifically challenging, the hypothesised mechanistic properties of aerobic exercise to inhibit recurrence appear biologically plausible ( National Cancer Institute, 2013 ). As such, given the cost-effectiveness of this strategy, research to elucidate the effects, mechanism, and optimal biologically effective dose in conjunction with research on how to effectively promote, deliver, and maintain exercise would be a prudent investment.