Coffee could prove to be a powerful medicine for bowel cancer patients.
A study found the disease was almost half as likely to return in men and women who drank at least four or five mugs a day.
It is thought the caffeine cuts inflammation which the cancer feeds on.
Cure: Scientists discovered that people who drank more than four mugs of coffee a day were a third less likely to die from cancer
The research, from the Dana Farber Cancer Institute in Boston, found that consuming around 460mg of caffeine a day cut the odds of bowel cancer coming back by 42 per cent.
It also made people 33 per cent less likely to die from cancer or any other cause.
Smaller amounts of caffeine brought lower benefits.
A mug of instant coffee contains around 100mg of caffeine and an espresso, the base for many High Street coffees, 80mg.
Writing in the Journal of Clinical Oncology, researcher Dr Charles Fuchs said: ‘We found that coffee drinkers had a lower risk of the cancer coming back and a significantly greater survival and chance of a cure.
‘If you are a coffee drinker and are being treated for colon cancer, don't stop.
‘But if you're not a coffee drinker and wondering whether to start, you should first discuss it with your physician.’
The study of 1,000 patients was the first to examine an association between caffeinated coffee and risk of colon cancer recurrence.
Medicine: Scientists found the caffeine in coffee reduced the risk of the cancer returning when people drank four or more mugs a day
It adds to a number of recent studies suggesting that coffee may have protective effects against the development of several kinds of cancer, including reduced risks of postmenopausal breast cancer, melanoma, liver cancer and advanced prostate cancer.
Researchers found the drink had also been shown to reduce the risk of type 2 diabetes.
Scientists believe that the lowered risk of cancer recurrence and deaths was entirely due to caffeine and not other components of coffee.
It is not yet clear why caffeine had this effect on patients.
One theory is that caffeine consumption increases the body's sensitivity to insulin so less of it is needed, which in turn may help reduce inflammation - a risk factor for diabetes and cancer, Dr Fuchs said.
Avoiding obesity, exercising regularly, adopting a healthier diet, and eating nuts - which also reduce the risk of diabetes - are recommended to lower the risk of cancer.