December 23, 2012
People who drink four or more cups of caffeinated coffee each day have only half the risk of dying from oral or pharyngeal cancer when compared to those who drink less, according to a new American Cancer Society study published in the American Journal of Epidemiology.
Prior studies have found that higher levels of coffee consumption are correlated with a lower risk of contracting oral and pharyngeal cancer. For example, a study published in the journal Cancer Epidemiology Biomarkers and Prevention in November found that coffee drinkers (as long as they had fewer than five cups a day) were 39 percent less likely to develop cancer of the mouth or throat than non-coffee drinkers – although the effect was weaker in those who regularly smoked or drank liquor. The researchers noted that scientists have identified more than a thousand natural coffee chemicals that may have cancer-fighting properties.
In the American Cancer Society study, researchers looked for a connection between rates of death from oral or pharyngeal cancer and consumption of tea, caffeinated coffee and decaffeinated coffee. The researchers used data from the Cancer Prevention Study II, a long-term study launched by the society in 1982.
“Coffee is one of the most widely consumed beverages in the world, and contains a variety of antioxidants, polyphenols, and other biologically active compounds that may help to protect against development or progression of cancers,” lead author Janet Hildebrand said.
Four cups a day, half the risk
The researchers examined 968,432 adults who were cancer-free as of 1982. In the intervening 26 years, 868 of the study’s participants died of mouth or throat cancer. Using this data, the researchers found that people who drank four cups or more of caffeinated coffee each day were 49 percent less likely to die from throat or mouth cancer than people who never drank coffee or only occasionally. In fact, every cup per day that a person consumed significantly decreased the risk of death, even after the researchers corrected for sex, alcohol use or smoking.
The researchers also found evidence that consuming two or more cups of decaffeinated coffee per day might similarly reduce the risk of death from cancer, but the findings were not statistically significant enough for the researchers to declare confidence in them. No connection was found between tea consumption and cancer death.
Because the study only looked at correlation, it could not determine whether coffee consumption directly causes the observed reduction in risk of death. Even if coffee does directly reduce a person’s risk of dying from these cancers, it remains to be seen whether it does so by reducing the risk of contracting the cancer, improving the prognosis or both.
“Although it is less common in the United States, oral/pharyngeal cancer is among the ten most common cancers in the world,” Hildebrand said. “Our finding strengthens the evidence of a possible protective effect of caffeinated coffee in the etiology and/or progression of cancers of the mouth and pharynx.”