Association between Different Types of Tea Consumption and Risk of Gynecologic Cancer: A Meta-Analysis of Cohort Studies

Plenty of studies have shown that tea has an effect of inhibiting gynecologic tumors. However, there still remained controversy of the association between tea and gynecologic tumors in epidemiological studies. In this study, PubMed, Embase, and Cochrane Database were used to search the literature from 1 January 1960 to 26 December 2022 to investigate the association between tea intake and gynecologic cancer risk. In total, 19 cohort studies with 2,020,980 subjects and 12,155 gynecological tumor cases were retrieved. The pooled relative risk (RR) of gynecologic tumor for tea intake was 1.00 (95% CI: 0.96-1.04). RRs were 0.94 (95% CI: 0.88-1.01) for ovarian cancer, 1.02 (95% CI: 0.97-1.07) for endometrial cancer, and 1.06 (95% CI: 0.91-1.23) for cervical cancer. Subgroup analyses were adopted based on the tea type and geographic location. Interestingly, significant preventive impact of non-herbal tea on ovarian cancer (pooled relative risk: 0.67; 95% CI: 0.55-0.81) was found, especially for black tea (pooled relative risk: 0.64; 95% CI: 0.51-0.80). Dose-response analysis indicated that although it is not statistically significant, a decreasing trend of ovarian cancer risk could be observed when the tea consumption was 1.40 to 3.12 cups/day. In conclusion, our findings suggested that ovarian cancer, but not other gynecologic cancers, could possibly be prevented by drinking non-herbal tea. In addition, the preventive impact of green tea on gynecologic cancer seemed to be relatively weak and needs further cohorts to validate it.