Walking for just 30 minutes a day can boost the chances of beating cancer by almost half, research shows.
Separate studies involving breast and bowel cancer patients found that regular exercise had a huge impact on survival.
The first was carried out by a team from Harvard University who followed 992 men with stage three bowel cancer, which had spread to nearby tissue, for seven years.
Stage three is the second most advanced form of cancer, meaning it is large and fast-growing.
Patients who did 30 minutes' moderate exercise five days a week and ate healthily were 42 per cent less likely to die. They also lived longer if the cancer returned.
The second study, by Australian researchers, looked at 194 women who had recently undergone surgery to remove breast cancer.
Half of patients were told to do 180 minutes' moderate activity a week for at least eight months although many carried on for longer.
The other half continued about their normal lives and both groups were examined after eight years.
The team from the Queensland University of Technology in Brisbane found that women who had exercised were 55 per cent more likely to still be alive.
The majority of patients in both studies did brisk walking as their main activity but heavy cleaning, gentle cycling and mowing the lawn also counted.
Scientists believe that even moderate exercise can slow tumour growth or prevent their returning by reducing levels of hormones.
They include insulin, which helps tumour cells multiply, as well as oestrogen in women, which encourages the development of breast cancer.
Exercise is particularly important for bowel cancer as it reduces inflammation, which can lead to cells multiplying and forming tumours. It also prevents patients becoming obese, as fat tissue produces hormones that stimulate tumour growth.
The bowel cancer study was presented at the American Society of Clinical Oncology conference in Chicago, the world's largest cancer meeting.
Dr Erin van Blarigan, associate professor at the University of California, San Francisco, who led the study alongside Harvard academics, said: Patients should build up to exercising for at least 150 minutes per week. Doctors absolutely should counsel patients to exercise.'
Dr Vicky Coyle, a Cancer Research UK scientist at Queen's University Belfast, said: Patients with advanced bowel cancer could benefit from keeping a healthy weight, being physically active, and eating a healthy diet, as this study suggests.'
Responding to the study on breast cancer, Baroness Delyth Morgan, chief executive of the charity Breast Cancer Now, said: These preliminary findings add to the increasing body of evidence suggesting that exercise could improve the chances of survival.'
The NHS advises patients to do at least 150 minutes of moderate activity a week.
© Daily Mail