Another win for java in the should-you/shouldn't-you debate. New data showed that patients with colon cancer who drank four or more cups of coffee a day were less likely to have their cancers recur or to die compared with patients with colon cancer who did not regularly drink coffee (JCO 2015 doi: 10.1200/JCO.2015.61.5062).
Previous studies have shown that diet and lifestyle do influence an individual's risk for developing colon cancer, noted the study's corresponding author, Charles Fuchs, MD, MPH, Director of the Gastrointestinal Cancer Center and Institute Physician at Dana-Farber Cancer Institute and Professor of Medicine at Harvard Medical School. "But it's a bit of an inference to conclude that those studies necessarily inform how patients with colon cancer would do with any particular diet modification.
"So we decided to prospectively look at diet and lifestyle, and as it relates to cancer risk, get the same data for a population of patients being treated for cancer to see which diet and lifestyle choices might influence the ultimate outcome from their cancer."
And as he and his colleagues hypothesized, similar to how it has been shown to play a role in colon cancer risk, coffee also appears to play a role in outcomes for patients who have been diagnosed with colon cancer.
The researchers analyzed data from a cohort of 953 patients with stage III colon cancer from the Cancer and Leukemia Group B (Alliance) 89803 study for which patients prospectively completed food frequency questionnaires four months after surgery (at which point they were receiving chemotherapy) and six months after completion of chemotherapy. Compared with patients who drank no coffee, patients who reported consuming four cups or more of caffeinated coffee per day had a 45 percent reduction in risk for cancer recurrence and a 46 percent reduction in risk of death from any cause. The researchers adjusted risk for sugar-sweetened beverage intake and glycemic load, which their previous work had showed also play a role in outcomes for patients with colon cancer.
The team also compared the effects of caffeinated coffee versus decaffeinated coffee and found that when analyzing decaffeinated coffee consumption alone, there was no link to improved outcomes.
While those findings might mean that caffeinated coffee yields a benefit in terms of colon cancer outcomes that decaffeinated coffee does not-it also might be the case that the low number of decaffeinated coffee drinkers in the study was inadequate to statistically show a benefit, Fuchs explained.
The bottom line, he said: "Patients who were regular caffeinated coffee drinkers had a significant improvement in their outcomes-namely a lower risk of cancer recurrence and a better survival."
Why? Here's what he told OT in a phone interview.
1. You said it was an "inference" that the diet and lifestyle choices that influence colon cancer risk would also influence colon cancer outcomes-why did you suspect there might be a connection?
"CALGB 89803 started in order to collect dietary information in this population of stage III colon cancer patients. We found over time that a number of factors do influence outcomes for these patients-namely, that patients who are obese and who are sedentary do worse, and patients who avoid exercise and exercise regularly have better outcomes. And in this cohort of patients [for which coffee consumption was followed], we also found that consumption of sugar-sweetened beverages was associated with worse outcomes; and having a high glycemic load diet was associated with worse outcomes.
"Many of these factors seemed to be risk factors for the development of type 2 diabetes. And what's curious is that other research has shown that people who have a history of type 2 diabetes actually do worse from colon cancer. So we wanted to look and see whether factors that influence diabetes risk could influence outcomes for patients with colon cancer.
"And coffee has-relatively consistently-been a factor associated with lowering the glycemic risk of type 2 diabetes-so that was the motivation to look at coffee consumption."
2. So what is the mechanism for coffee having this protective effect?
"We suspect that given that we're now consistently finding the risk factors for diabetes having a similar modifying risk on outcomes for these patients with colon cancer, we are at least hypothesizing that the ability of coffee to improve outcomes may be through that pathway.
"At a mechanistic level how is it doing that? We don't know yet. What component of coffee might be contributing to the benefit? We don't know. And what pathway is it influencing in colon cancer that might improve outcomes?
"Those are very important questions. Not only does it give you better insight into the nature of the causality, but it also gives potential clues toward better treatments. We believe that these pathways-referred to as energy-balance pathways or the pathways that relate to diabetes and glucose metabolism-are relevant. And if we understand what the target of these 'interventions' (in this case, coffee) is in the cancer cells, then potentially we could come up with a more sophisticated and targeted approach that might benefit these patients even more beyond these lifestyle habits."
3. So what is the message to practicing oncologists about whether or not patients with colon cancer should drink coffee?
"The findings do require confirmation. This is one study-it has a fair number of patients and it's prospective in its design in that we collected the information on diet and lifestyle before we knew anything about the individual outcomes for patients-but you want to see a confirmatory study; and we are in the process of planning that.
"Right now for patients who have been recently diagnosed with colon cancer and enjoy coffee, I would say, don't stop drinking it. This study suggests there may be a genuine benefit. If someone says, I hate the stuff, I would say, then don't drink it.
"As stated in the paper, regular exercise, avoiding obesity, avoiding a high glycemic load diet, avoiding sugar-sweetened beverages, and avoiding an excessive Western diet all also seem to contribute to a meaningful benefit. So I wouldn't tell somebody to start drinking coffee if that's not something they're already inclined to do."