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

OBJECTIVE

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.