Coffee Consumption and Risk of Prostate Cancer in Local, Advanced, and Fatal Grades: A Meta-Epidemiological Study of Prospective Cohort Studies

ABSTRACT

There were conflict reports among the previous systematic reviews conducted to evaluate the association between coffee consumption and risk of prostate cancer. This meta-epidemiological study aimed to evaluate the reasons for conflicting findings among previous studies and then estimate a more valid summary effect size of the association between coffee consumption and prostate cancer risk in grades and all cases. The selection criteria were defined that a prospective cohort study conducted to evaluate coffee consumption and risk of prostate cancer incidence with reporting adjusted relative risk (RR) and its 95% confidence interval (95% CI). Random effect model meta-analysis and 2-stage fixed-effect dose-response meta-analysis were performed by cancer grades. From a total of 12 prospective cohort studies were selected, 11 all, 4 local, 5 advanced, and 4 fatal cohorts were organized. There was an inverse association between coffee consumption and the risk of prostate cancer in all cases with statistical significance (summary RR, 0.91; 95% CI, 0.84–0.98; I-squared=49.1%). Dose-response meta-analysis showed that the unit’s decreasing risk levels were 1.0 % in all cases, 1.1% in localized cases, and 2.5% in fatal cases, respectively. There is an inverse association between coffee consumption and risk of prostate cancer in local and fatal grades, not in advanced grade. And the main reasons for conflict results among the previous studies would be due to noncomprehensive searching strategies, the interdifferent definition of selection criteria, inaccurate extraction of information, and inadequate adjustment for potential confounders.