Drinking four or more cups of coffee daily may significantly prevent the return of colon cancer after treatment and improve the chances of a cure, a large new study has claimed.
The research is the first to study an association between caffeinated coffee and risk of colon cancer recurrence, researchers said.
The patients, all of them treated with surgery and chemotherapy for stage III colon cancer, had the greatest benefit from consuming four or more cups of coffee a day (about 460 milligrammes of caffeine).
These patients were 42 per cent less likely to have their cancer return than non-coffee drinkers, and were 33 per cent less likely to die from cancer or any other cause.
Two to three cups of coffee daily had a more modest benefit, while little protection was associated with one cup or less, the researchers said.
The study included nearly 1,000 patients who filled out dietary pattern questionnaires early in the study, during chemotherapy and again about a year later.
"We found that coffee drinkers had a lower risk of the cancer coming back and a significantly greater survival and chance of a cure," said Charles Fuchs, director of the Gastrointestinal Cancer Centre at Dana-Farber Cancer Institute in Boston.
Most recurrences happen within five years of treatment and are uncommon after that, he noted.
In patients with stage III disease, the cancer has been found in the lymph nodes near the original tumour but there are no signs of further metastasis. Fuchs said these patients have about a 35 per cent chance of recurrence.
However, Fuchs is hesitant to make recommendations to patients until the results are confirmed in other studies.
A number of recent studies suggested that coffee may have protective effects against the development of several kinds of cancer, including reduced risks of postmenopausal breast cancer, melanoma, liver cancer, advanced prostate cancer.
Fuchs said the research focused on coffee and other dietary factors because coffee drinking - in addition to possibly being protective against some cancers - had been shown to reduce the risk of type 2 diabetes.
In analysing the results of the new study, Fuchs and his colleagues discovered that the lowered risk of cancer recurrence and deaths was entirely due to caffeine and not other components of coffee.
He said it's not clear why caffeine has this effect and the question needs further study.
One hypothesis 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, Fuchs said.
The study was published in the Journal of Clinical Oncology.
