Americans drink about 12.8 billion gallons of coffee every year, which is enough to flood the city of Dubuque, Iowa, to a depth of 2 feet, not counting the milk and sugar. What are we getting from all that java besides a kick-start in the morning? Research shows that coffee may help prevent certain cancers as well as reduce cancer mortality.
Over the past several years, a number of studies have documented a link between coffee consumption and reduced risk of oral/pharyngeal cancer. Now, investigators in the Epidemiology Research Program of the American Cancer Society have taken the next step in this line of research and established that drinking coffee reduces the risk of oral/pharyngeal cancer mortality.
The study authors analyzed data from the Cancer Prevention Study II, a prospective cohort study begun in 1982 that included almost 1 million subjects who were free of cancer at enrollment. During 26 years of follow-up, 868 subjects died from oral/pharyngeal cancer. Questioning subjects on their coffee consumption revealed that those who drank four cups or more of caffeinated coffee per day had a 49% lower risk of death from oral/pharyngeal cancer than those who drank coffee occasionally or never. There was a dose-related decline in oral/pharyngeal cancer death with each cup of coffee consumed. A relationship not-quite as significant was found between drinking two or more cups of decaffeinated coffee per day and reduced risk of death. In this study, however, drinking tea had no effect on death from oral/pharyngeal cancer. But why?
Coffee contains several biologically active compounds that may protect against oxidative DNA damage, promote apoptosis, and have antiproliferative activity.
In 2011, a pooled analysis of one cohort study and eight case-control studies found a 39% reduction in the incidence of oral/pharyngeal cancer for the highest category of coffee consumption compared with the lowest, but no relationship between coffee drinking and the incidence of laryngeal or esophageal cancer. In a similar pooled analysis of nine case-control studies, drinkers of four cups or more of caffeinated coffee per day also had a 39% risk reduction for oral/pharyngeal cancer compared with those who didn’t drink coffee. A case-control study conducted in Japan found a reduced risk of oral, pharyngeal, and esophageal cancer in subjects who drank at least one cup of coffee per day, and an analysis of data from two case-control studies found that high consumption of coffee was even more effective than eating fruit and vegetables in the prevention of oral cancer.
In these analyses the protective effect of coffee drinking was seen in both smokers and non-smokers, although there were very few of the latter in the populations with oral/pharyngeal cancer.
However, the relationship between coffee and cancer isn’t a simple one. An analysis of data collected from almost half a million people age 50 to 71 years who participated in the National Institutes of Health/AARP study found that coffee drinking had no effect on the incidence of oral/pharyngeal cancer but raised the risk for cancer of the gastric cardia; the study found a reduced risk of esophageal adenocarcinoma during certain periods of follow-up. Interestingly, drinking hot tea, but not iced tea, reduced the risk of oral/pharyngeal cancer. A more recent analysis of data from the same study found that drinking coffee reduced overall mortality, but not cancer mortality.