Can the simple act of drinking caffeinated coffee reduce the risk for colon cancer's return and subsequent death?
A new prospective and observational study suggests the answer is yes, but, as always with such research, the findings only reveal correlations and are not proof of causation.
In other words, clinicians cannot necessarily recommend coffee to patients with colon cancer on the basis of this study.
"If you are a coffee drinker and are being treated for colon cancer, don't stop," said senior author Charles Fuchs, MD, MPH, from the of Dana-Farber Cancer Institute in Boston, in a press statement. However, he added, noncoffee drinkers should not necessarily start, unless they consult their physician.
The study, the first to look at coffee drinking and colon cancer outcomes, was published online August17 in the Journal of Clinical Oncology.
The clinical trial, sponsored by the National Cancer Institute, examined outcomes in patients with stageIII colon cancer who were treated with surgery and various chemotherapies. All 953 patients reported their intake habits for 128 foods, including caffeinated coffee, decaffeinated coffee, and nonherbal tea, during and 6 months after chemotherapy.
The benefit was strongest in the heaviest drinkers of caffeinated coffee. Patients who consumed at least four cups of coffee a day (about 460mg of caffeine) were 52% less likely to have their cancer return or to die than noncoffee drinkers (adjusted hazard ratio, 0.48; Ptrend = .002).
Patients who drank fewer cups of caffeinated coffee also saw a benefit, but the degree of risk reduction tapered as the average number of cups per day dropped. In other words, there was a doseresponse effect.
There was no association between improved outcomes and decaffeinated coffee or nonherbal tea.
However, "total coffee intake" both caffeinated and decaffeinated coffee was associated with improved outcomes. But, as might be expected, the improvements were less substantial than those seen in patients who drank only caffeinated coffee.
"We found that coffee drinkers had a lower risk of the cancer coming back and a significantly greater survival and chance of a cure," Dr Fuchs reported. Most recurrences happen within 5 years of treatment and are uncommon thereafter, he pointed out.
In the study cohort, 62 patients drank at least four cups of some kind of coffee a day, 313 drank two or three cups, 238 drank only one cup, and 154 drank no coffee.
Various studies in recent years have suggested that coffee protects against the development of breast cancer and skin cancer, and protects against the recurrence or progression of prostate cancer. But the medical literature is mixed in its reports of coffee's effect on the risk of developing colon cancer.
The studies with positive findings were not the inspiration for the current study. Instead, the authors hypothesized that "coffee might reduce colon cancer recurrence through improved insulin sensitization and decreased hyperinsulinemia, on the basis of previous studies supporting the role of high-energy balance states in promoting colon cancer recurrence and mortality."
Coauthor Brendan Guercio, MD, from Brigham and Women's Hospital in Boston, expanded on the specifics of this theory.
"Excess energy balance refers to taking in more calories than are expended," he told Medscape Medical News. This often occurs with high-calorie diets and sedentary lifestyles, and results in obesity and diseases such as type2 diabetes.
"Excess energy balance is associated with poorer prognoses in patients with colon cancer, regarding both survival and disease recurrence," Dr Guercio explained, adding that a growing body of data suggests as much.
The research was supported by the National Institutes of Health and Pfizer Oncology. Some of the study authors report ties to the pharmaceutical industry.
J Clin Oncol. Published online August17, 2015. Abstract
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