A quart of coffee a day keeps colon cancer away. That’s the message from a first-of-its-kind study that found that patients with stage III colon cancer who drank more coffee had significantly fewer cancer recurrences and deaths compared with similar patients who didn’t drink coffee.
The more cups of caffeinated coffee the patient drank, the better the outcome, according to the new study, published August 17, 2015 in the Journal of Clinical Oncology. The study included nearly 1,000 colon cancer patients who filled out dietary pattern questionnaires 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 the study’s leader Charles S. Fuchs, MD, MPH, director of the Gastrointestinal Cancer Center at Dana-Farber Cancer Institute, in Boston, MA.
Results showed that patients who consumed four or more cups of coffee a day (about 460 milligrams of caffeine) had the greatest benefit. They were 42% less likely to have a recurrence than non-coffee drinkers, and were 34% less likely to die from cancer or any other cause.
Two to three cups of coffee a day provided a more modest benefit, while one cup or less offered little to no protection, the researchers reported. The study is the first to examine an association between caffeinated coffee and risk of colon cancer recurrence.
Although the results appear to be straightforward, Dr. Fuchs declines to make specific recommendations until the research is confirmed by other studies. For now, he offers some basic advice: "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."
In analyzing the results, Dr. Fuchs and his colleagues determined that the lowered risk of cancer recurrence and deaths was due entirely to caffeine and no other components in coffee. Non-herbal tea and decaffeinated coffee, for instance, didn’t show improved outcomes in patients with colon cancer.
It's not clear why caffeine has this effect, Dr. Fuchs said, but the question merits further study. One hypothesis is that caffeine consumption increases the body's sensitivity to insulin so less of it is required, which in turn may help reduce inflammation—a risk factor for diabetes and cancer.
Greater coffee consumption has already been associated with decreased risk of type 2 diabetes and increased insulin sensitivity, the researchers noted. Risk factors for diabetes—obesity, sedentary life style, a Western diet high in calories and sugar, and high levels of insulin—are also implicated in colon cancer.
Besides drinking coffee, people can take other steps to reduce cancer risks, such as avoiding obesity, exercising regularly, adopting a healthier diet, and eating nuts—measures that also reduce the risk of diabetes, Dr. Fuchs said.