Aerobic exercise can help relieve the fatigue often associated with cancer and cancer treatment, according to Cochrane researchers. Their updated systematic review strengthens findings from an earlier version on cancer-related fatigue published in The Cochrane Library.

Fatigue is a common and potentially long-lasting side-effect of cancer and cancer treatment. It may last for months or years. Dealing with cancer-related fatigue is crucial because those who suffer its effects may be less inclined to continue with treatment. Although in the past, people with cancer-related fatigue have been advised to rest, long periods of inactivity may lead to muscle wasting and increased tiredness, whereas balancing rest with physical activity may help to reduce fatigue. A 2008 Cochrane systematic review on the benefits of exercise found some benefits of physical activity for fatigue in cancer based on limited studies.

The new review adds a further 28 studies to those included in the 2008 review. Altogether, 56 studies involving a total of 4,068 people with cancer were included. Half of the studies were carried out in people with breast cancer. Those with solid tumours benefited from aerobic exercise, such as walking or cycling, both during and after cancer treatment. Other forms of exercise, including resistance training, did not significantly reduce fatigue.

"The evidence suggests that exercise may help reduce cancer-related fatigue and should therefore be considered as one component of a strategy for managing fatigue that may include a range of other interventions and education," said lead researcher Fiona Cramp of the Faculty of Health & Life Sciences at the University of the West of England in Bristol, UK. "This updated review provides a more precise conclusion, showing specifically that aerobic exercise, both during and after cancer treatment, can be beneficial."

It remains to be seen how cancer treatment alters the beneficial effects of exercise on cancer-related fatigue. Further research is also needed to understand how the frequency and duration of exercise, and type of cancer, affect the results. "Twenty eight of the studies we included were carried out in breast cancer patients, so we need to know more about how exercise can help people with a broad range of diagnoses, including patients with advanced disease," said Cramp.

The research was funded by the UK's National Institute for Health Research (NIHR) Health Technology Assessment programme.