Coffee drinkers who consume four or more cups of java a day are significantly less likely to have a recurrence of their colon cancer, researchers say.

Four cups a day translated to a 42 percent reduced chance of a recurrence, say researchers at the Dana-Farber Cancer Center in Boston conducting a study of almost 1,000 stage 3 colon cancer patients.

Two or three cups a day offered some, but slightly less benefit, while patients who kept their consumption to one cup a day saw no benefits from their coffee habit, the researchers reported in the Journal of Clinical Oncology.

"If you're a coffee drinker and are being treated for colon cancer, don't stop," suggested Charles Fuchs, head of Dana-Farber's Gastrointestinal Cancer Center.

In the colon cancer study sponsored by the National Cancer Institute, researchers looked at the effects of more than 100 beverages and food on the cancer patients undergoing treatment for their disease.

It is unclear at the moment exactly why heavy consumption offers a benefit to coffee-drinking cancer patients, the researchers acknowledge.

They suggest it's not the coffee but the caffeine it contains, which may be increasing patients' insulin sensitivity.

That may be allowing the body to function appropriately on less insulin, which may mean decreased inflammation, leading to a reduced recurrence of their colon cancer.

Still, experts say, even this preliminary study suggests further research is warranted.

"Yes, this was a carefully done study that does suggest that coffee certainly isn't harmful and there's certainly some value for patients," said Dr. Andrew Chan, a professor of medicine at both Harvard Medical School and Massachusetts General Hospital in Boston. "But I'm not sure that the apparent benefit of coffee is clear enough yet to warrant any clinical recommendations."

"That will require additional research to establish causality."

Previous studies have suggested coffee offers some protection against the development of breast cancer and skin cancer, and can possibly reduce the recurrence or progression of prostate cancer.

However, the researchers suggest that colon cancer patients who aren't coffee drinkers consult with their primary physician before taking up the habit.

The research has suggested an association between coffee consumption and reduced colon cancer recurrence, but that is not the same thing as confirming a cause and effect, they emphasize.

It would be unwise to assume that coffee can reduce the risk of the deadly disease until further study has been made, they caution.