Drinking regular cups of caffeinated coffee could increase a person's chances of surviving bowel cancer, research has shown.
A study of nearly 1,000 treated patients found that those who consumed four or more cups of coffee a day were 42% less likely to see their cancer return than non-coffee drinkers.
They were also 33% less likely to die from cancer or any other cause.
The effect of coffee was dose responsive, increasing as more of the beverage was consumed. Two to three cups a day produced a more modest benefit, while one cup or less offered little protection.
Lead scientist Dr Charles Fuchs, director of the Gastrointestinal Cancer Centre at the Dana-Farber Cancer Institute in the US, 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."
All the patients had stage III bowel cancer, meaning the disease had spread as far as the lymph nodes near the original tumour.
Under normal circumstances, such patients had a 35% chance of cancer recurrence after surgery and chemotherapy, said Dr Fuchs.
Despite the results, he was cautious about recommending coffee as a potential alternative treatment for people with bowel cancer.
"If you are a coffee drinker and are being treated for colon cancer, don't stop," he said. "But if you're not a coffee drinker and wondering whether to start, you should first discuss it with your physician."
The research, published in the Journal of Clinical Oncology, is the first to link caffeine to a reduced risk of bowel cancer recurrence.
Previous studies have suggested that coffee might protect against several kinds of cancer, including melanoma skin cancer, liver cancer and advanced prostate cancer.
Other research has shown that drinking coffee may reduce the risk of Type 2 diabetes, which shares bowel cancer risk factors including obesity, a sugary, high calorie diet, and high levels of the hormone insulin.
The new results showed that the reduced risk of cancer recurrence and death was entirely due to caffeine and not other components in coffee.
Why caffeine should have this protective effect is still unclear. One theory is that caffeine consumption increases the body's sensitivity to insulin, which in turn may help reduce inflammation.