Effect of exercise on tumor markers – Is exercise anti-tumorigenic in humans?: A scoping review of preliminary clinical investigations

It has been increasingly conceptualized that exercise may be able to suppress cancer progression itself based on the preclinical evidence suggesting various mechanisms. The challenges exist in investigating the effects of exercise on tumor progression in human settings. Circulating or tissue-driven tumor markers can be a useful and cost-effective tool in monitoring the progression of some cancers. This scoping review summarized the current evidence on the use of tumor markers in clinical exercise oncology trials. A total of 14 studies were identified, and tumor markers included prostate-specific antigen for prostate cancer, carcinoembryonic antigen and circulating tumor cells for colorectal cancer, and Ki-67 for breast cancer. Treatment settings and exercise prescriptions were highly heterogeneous, while most studies did not find significant exercise-mediated effects on tumor markers. Nevertheless, we provide an insight into the utility and considerations in using tumor markers in clinical exercise oncology research.