Ginkgo biloba and risk of cancer: secondary analysis of the Ginkgo Evaluation of Memory (GEM) Study.

PURPOSE: Evidence from in vitro and in vivo studies suggests that Ginkgo biloba has cancer chemopreventive properties, but epidemiological evidence is sparse. We analyzed cancer as a secondary endpoint in the Ginkgo Evaluation of Memory (GEM) Study, the largest randomized, double-blind, placebo-controlled clinical trial of Ginkgo supplementation to date.

METHODS: A total of 3069 GEM participants 75+ years of age were randomized to twice-daily doses of either 120 mg Ginkgo extract (EGb 761) or placebo and followed for a median 6.1 years. We identified hospitalizations for invasive cancer by reviewing hospital admission and discharge records for all reported hospitalizations over follow-up. Using an intention-to-treat approach, we compared the risk of cancer hospitalization between participants assigned to treatment and those assigned to placebo.

RESULTS: During the intervention, there were 148 cancer hospitalizations in the placebo group and 162 in the EGb 761 group (Hazard ratio (HR), 1.09; 95% confidence interval (CI), 0.87-1.36; p = 0.46). Among the site-specific cancers analyzed, we observed an increased risk of breast (HR, 2.15; 95%CI, 0.97-4.80; p = 0.06) and colorectal (HR, 1.62; 95%CI, 0.92-2.87; p = 0.10) cancer, and a reduced risk of prostate cancer (HR, 0.71; 95%CI, 0.43-1.17; p = 0.18).

CONCLUSIONS: Overall, these results do not support the hypothesis that regular use of Ginkgo biloba reduces the risk of cancer.