An apple a day keeps the doctor away. And now it seems that 4 cups of coffee a day may reduce recurrence and death in patients with stage III colon cancer after surgical resection and adjuvant chemotherapy, according to a study led by Brendan J. Guercio, MD, Harvard Medical School, Boston (Guercio BJ, et al. J Clin Oncol. 2015;33:3598-3607).
“We chose to investigate the relationship between coffee intake and outcomes in colon cancer, because other data suggest that coffee may be protective against developing diabetes, and that diabetes is associated with worse colon cancer patient outcomes,” Dr Guercio told Value-Based Cancer Care. The team of investigators believes this is the first study to examine this association. The study was funded by the National Cancer Institute.
They tested their hypothesis that drinking more coffee may benefit these patients using a patient-reported semiquantitative food frequency questionnaire that captured diet and lifestyle factors. Approximately 130 food items were included.
Patients completed the questionnaire 4 months after surgery and again 6 months after completing treatment. A total of 963 patients within the prospective CALGB 89803 (NCT00038350) study were included in this analysis. The patients had lymph node–positive, nonmetastatic cancer, and the mean follow-up was 7.3 years.
Patients in the CALGB 89803 study received fluorouracil plus leucovorin once weekly or irinotecan plus fluorouracil and leucovorin once weekly.
Significant Reduction in Recurrence, Death
Compared with patients who drank no coffee, patients who reported consuming ≥4 cups of caffeinated coffee daily had a 45% reduction in adjusted relative risk for cancer recurrence and a 46% reduction in adjusted relative risk for death from any cause.
No association was found between decaffeinated coffee or nonherbal tea and cancer recurrence or death from any cause.
The analysis showed a 34% reduction in cancer recurrence or mortality in the highest versus the lowest quintile of total caffeine intake; the recurrence-free survival and overall survival were also improved.
However, an observational study can demonstrate associations but not prove causality, because of the inability to rule out confounding by unmeasured variables. “We did reduce the likelihood of confounding by controlling for many variables that may impact general health and colon cancer outcomes,” stated Dr Guercio. Among the variables they controlled for were physical activity, smoking history, alcohol consumption, caloric intake, body mass index, sugar-sweetened beverage intake, dietary glycemic load, multivitamin use, and dietary patterns.
“These results suggest that if a person with colon cancer already enjoys drinking coffee, it may be prudent to continue doing so,” Dr Guercio said.
Yet, there is not sufficiently strong evidence from this one observational study to suggest that all patients with colon cancer must begin drinking coffee. “Instead, any patient who does not already drink coffee should make an informed decision through discussion with his or her physician,” he said. Other better-studied health benefits of coffee intake, such as its inverse association with incidence of type 2 diabetes, may also factor into this decision.
The investigators noted that the study results may potentially provide insights into colon cancer biology and into the role of diet and lifestyle in patients with colon cancer.