Coffee intake tied to reduced prostate cancer risk

A recent systematic review and meta-analysis suggested that increasing coffee consumption was tied to a reduced risk of prostate cancer.

“In this meta-analysis, higher coffee consumption was significantly associated with a reduced risk of prostate cancer. In the dose-response analysis, a reduction in the risk of prostate cancer of nearly 1 percent was observed for each increment of one cup of coffee per day,” noted the authors.

The results were based on analysis of 16 prospective cohort studies from North America, Europe, and Japan which included 1,081,586 men, of whom 57,732 developed prostate cancer. In each of the included studies, coffee consumption was determined through food frequency questionnaires or self-reported dietary questionnaires.

Overall, individuals with the highest category of coffee consumption had a 9 percent reduced risk of prostate cancer compared with the lowest category of consumption (pooled relative risk [RR], 0.91, 95 percent confidence interval [CI], 0.84–0.98; p=0.008; I²=53.2 percent*). [BMJ Open 2021;11:e038902]

There was a trend toward lower prostate cancer rates with increasing coffee consumption (pooled RR, 0.988, 95 percent CI, 0.981–0.995; p_{linear trend}=0.006 for each additional cup of coffee per day).

The reduction in risk with the highest vs lowest intake of coffee was evident for the different stages of prostate cancer ie, localized, advanced, and fatal cases of prostate cancer (pooled RR, 0.93, 95 percent CI, 0.87–0.99 [localized], pooled RR, 0.88, 95 percent CI, 0.71–1.09 [advanced], and pooled RR, 0.84, 95 percent CI, 0.66–1.08 [fatal]).

Reassessment of the comparisons in a sensitivity analysis which removed one study at a time did not appear to affect the findings.

Subgroup analysis of a previous meta-analysis suggested that coffee consumption was associated with a reduced risk of certain cancers such as bladder, breast, colorectal, endometrial, or hepatocellular cancer. [BMC Cancer 2011;11:96] However, the association between coffee consumption and prostate cancer risk was inconsistent, said the authors.

For example, the authors pointed out that the findings of the current analysis differed from a previous meta-analysis, where a higher risk of prostate cancer was observed with increasing coffee consumption in the analysis of case-control studies, and no apparent risk in the analysis of cohort studies. [BJU Int 2010;106:762-769]

This disparity may have been due to potential recall or selection bias in the case-control studies, the risk of which was reduced in the present analysis by the use of prospective cohort studies, said the authors. Nonetheless, potential confounders in the studies included in the present analysis may have affected the findings. The findings may also not apply to regions with a low incidence of prostate cancer, they added.

“It is biologically plausible that coffee may reduce the risk of prostate cancer,” said the authors. For example, coffee is a source of antioxidants and chlorogenic acids, has been associated with improved glucose metabolism and reduced plasma insulin concentration, and affects sex hormone levels. All of these play a role in the progression of prostate cancer, they said. [J Natl Cancer Inst 2011;103:876-884]

“[However,] further research is still warranted to explore the underlying mechanisms and active compounds in coffee,” the authors said.