Exercise interventions in metastatic cancer disease: a literature review and a brief discussion on current and future perspectives.

Exercise is a well-established factor which improves outcomes of oncological patients during curative treatment as well as in cancer survivors. However, the role of physical activity in metastatic disease, due to the deficiency of high-level evidence from prospective clinical trials, remains a partially unexplored field of research. Additionally, no specific guidelines related to exercise for persons with advanced cancer have been developed so far. Unfortunately, this research deficit may effectively prevent physicians from prescribing adequate and safe recommendations on physical activity to their patients. In an attempt to fill this gap in clinical practice, we present here an up-to-date review of potential benefits of exercise interventions in relation to the survival, quality of life and supportive care for patients with metastatic cancer. We also review the data on the safety of physical activity with special emphasis on elderly populations or individuals with bone metastases. Finally, we discuss the most relevant clinical factors that should be considered during exercise qualification. In conclusion, physical activity is an important tool for improving the outcomes of people undergoing anticancer therapy for metastatic disease. However, the training should be tailored individually to the patient's functional status, comorbidities and preferences. Physical activity should become a standard component of every metastatic cancer care plan.