Green tea extract prevents colorectal adenomas in males, but not in females - results of the MIRACLE trial

Background Epidemiological and experimental data suggest that green tea and especially its ingredient epigallocatechingallate (EGCG) has an antineoplastic effect in the colorectum.

Methods We performed a randomized, double-blind trial of decaffeinated green tea extract (GTE) standardized to 150mg of EGCG to prevent colorectal adenomas.

Setting The trial involved 40 German centres (hospitals and primary care setting) participating in the quality-assured national German CRC colonoscopy screening program.

Participants 1001 participants with histologically documented adenomas within the past 6 months were included.

Intervention After a 4-week run-in with GTE for safety assessment, 879 participants were subsequently randomized to receive GTE (n=432) or placebo (n=447) bid for 3 years. Follow-up colonoscopy was planned after 3 years. Primary endpoint was the presence of ≥1 adenoma or colorectal cancer at the follow-up colonoscopy.

Results Groups were well balanced with respect to baseline characteristics. The safety profile of GTE was favorable with no major differences in AEs. Adenoma rate in the modified intention-to-treat (mITT) set (n=632) was 55.7% in the placebo and 51.1% in the GTE group. This 4.6% difference was not statistically significant (adj. RR: 0.905; p=0.081). A preplanned analysis according to gender revealed an adenoma rate of 47.9% and 47.6% in the female placebo and GTE group, respectively (adj. RR: 1.019; p=0.894). In male participants adenoma rate was 60.4% in the placebo and 52.9% in the GTE group (adj. RR: 0.846; p=0.048).

Conclusion GTE was well tolerated and had overall a moderate chemopreventive effect on colorectal adenomas. There was only a significant effect in male participants pointing to a gender specific difference in chemoprevention.

(Trial registration: ClinicalTrials.gov, NCT01360320)

Publication History

Article published online:
07 September 2021