By Alan Mozes
Of the nearly 1,200 patients in the study, those who drank four or more cups of java on a daily basis had 36% higher odds of surviving during the 13-year study period.
Metastatic colon cancer, which has spread from its original location, "remains an incurable disease in most cases," explained study co-lead author Christopher Mackintosh, a fourth-year medical student at the Mayo Clinic School of Medicine in Phoenix.
"However, a number of lifestyle factors such as diet and exercise have been associated with prolonged life span for those dealing with the disease," Mackintosh noted. "Our study found that patients being treated with chemotherapy for metastatic colorectal cancers who drank coffee saw a longer period of time before both growth of their cancer and before death."
All the participants were part of a larger cancer treatment study conducted between 2005 and 2018. During that time, food and beverage intake was noted.
Researchers ultimately found that the more coffee consumed, the greater the survival benefit. For example, Mackintosh noted that patients who consumed up to a single cup of coffee per day tended to survive 30 months post-diagnosis. But those who drank two or three cups daily survived 32 months. And those who consumed four or more cups a day saw their survival shoot up to 39 months.
More was also more when it came to slowing cancer progression, the investigators found. Those who drank between two and three cups per day saw their disease status worsen more slowly than those who drank a cup or less. Similarly, disease progression slowed down even more among patients who routinely drank four or more cups of coffee daily.
The protective benefit held, regardless of whether patients drank caffeinated or decaffeinated coffee. And the findings build on prior research that has previously identified a similar protective link between coffee and cancer progression among colon cancer patients whose disease had not spread. "[But] to our knowledge, this is the first study on the effects of coffee on metastatic colorectal cancer patients," Mackintosh noted.
The findings were published online Sept. 17 in the journal JAMA Oncology.
Still, the researchers cautioned that although their work pinpoints a link between coffee and better cancer outcomes, it does not prove that drinking coffee actually causes mortality risk to drop or colon cancer growth to slow.
And Mackintosh explicitly cautioned colon cancer patients "against drastically increasing their coffee consumption just because of this study."
Instead, he suggested that "if someone is a colorectal cancer patient and enjoys drinking coffee, they can continue to do so without fear of worsening cancer prognosis. Of course, decisions like these should always be discussed on a case-by-case basis with one's personal health care professionals."
That thought was seconded by Erikka Loftfield, a research fellow in the division of cancer epidemiology and genetics with the U.S. National Cancer Institute's metabolic epidemiology branch in Rockville, Md.
Loftfield, who coauthored an accompanying editorial, agreed that the findings "do not indicate that people should start drinking coffee, but they may reassure colorectal cancer survivors who already do enjoy their coffee."
As to what might explain the association between coffee and improved cancer outcomes, Loftfield pointed out that "coffee contains more than a thousand chemical compounds, many of which have known bioactive potential. For example, polyphenols in coffee may have antioxidant and anti-inflammatory effects, and caffeine may increase gut motility."
Mackintosh and his colleagues also theorized about the potential cancer-impeding impact of antioxidants, while additionally highlighting the disease-fighting benefits that might arise from caffeine's effect on insulin secretion.
That later point was echoed by Dr. Andrew Chan, a professor in the department of medicine at both Harvard Medical School and Massachusetts General Hospital in Boston, who reviewed the study. "Coffee is known to have anti-inflammatory properties and to sensitize tissues to the effects of insulin, which helps regulate our blood sugar," he explained. "These are both mechanisms that may reduce the risk of cancer."
But both Loftfield and Mackintosh agreed that more research will be needed to get a firmer handle on coffee's precise role in advanced colon cancer progression.
"For the time being, I would suggest those who enjoy drinking coffee continue to do so, and I would not suggest that those who do not drink coffee begin doing so for perceived health benefits," Mackintosh said.