High coffee intake may raise prostate cancer risk in tobacco smokers

Key takeaways:

• High coffee consumption was linked to a 19% increased risk for prostate cancer in men who smoke.
• More research is needed to support this finding, as it differentiates from previous data.

CHICAGO — Drinking more than eight cups of coffee per day significantly increased the risk for prostate cancer among men who smoke tobacco, according to research presented at the annual NUTRITION meeting.

There are few established prostate cancer risk factors, which include genetics, family history and age, Stephanie J. Weinstein, PhD, a staff scientist in the metabolic epidemiology branch at the National Cancer Institute, told Healio. But it is the third most common cancer among men worldwide and the most common cancer among men in the United States.

“Increased coffee drinking has been associated with reduced risk for some malignancies, such as endometrial, brain, kidney, skin [melanoma and non-melanoma] and liver, but there is only weak evidence regarding prostate cancer,” Weinstein said. “Coffee is consumed by 65% of the U.S. population, and Finland ranks second in the world for coffee consumption.”

Weinstein and colleagues analyzed a cohort of 27,111 male tobacco smokers in Finland aged 50 to 69 years from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, which included self-reported data on coffee consumption.

During the 30 years of follow up, 2,584 men were diagnosed with prostate cancer.

The researchers found that, at very high levels of coffee intake (eight or more cups per day), the risk for prostate cancer “was significantly elevated” by 19% compared with the lowest levels of coffee consumption (zero to two cups per day).

Noncoffee drinkers had the lowest risk for prostate cancer (HR = 0.82; 95% CI, 0.59-1.12), while higher risks were observed in those who drank:

• One to two cups per day (HR = 1; 95% CI, 0.87-1.16);
• Two to four cups per day (HR = 0.99; 95% CI, 0.86-1.14);
• Four to six cups per day (HR = 1.03; 95% CI, 0.9-1.18);
• Six to eight cups per day (HR = 1.1; 95% CI, 0.94-1.29); and
• Eight or more cups per day (HR = 1.19; 95% CI, 1.02-1.28).

“Men who smoke should consider cutting back on their coffee intake if it is very high, and certainly smoking cessation [or never taking up smoking] would have a substantial impact on reducing lifetime risk for cancer and other adverse health outcomes,” Weinstein said.

However, the findings differ from other research, according to Weinstein.

Most studies on the subject “report either no coffee-prostate cancer risk association, or possibly lower risk among men with higher coffee consumption,” she said. But this investigation “differed from other studies, as it comprised male Finnish smokers who drank a lot of coffee daily.”

“Although the coffee/prostate cancer risk association was similar when we examined it separately by smoking intensity — that is, by greater or fewer cigarettes smoked daily, or by cumulative years of smoking — the increased prostate cancer risk we observed for men with the highest daily coffee consumption may only be relevant to smokers,” Weinstein said.