Cancer and treatment of cancer affects the health-related quality of life (HRQoL) in patients. A recent Cochrane review concludes that exercise may have positive effects on HRQoL and several other domains. Other reviews have shown that physical activity may protect against development of cancer and reduces risk of recurrence and mortality from breast- and colon cancer. Considerable efforts go to patient care and rehabilitation, both during and after cancer treatment. This new systematic review implies that exercise programmes should be a central part of rehabilitation for all cancer patients.