Green Tea Supplement Does Not Impact Tamoxifen Pharmacokinetics in Women with Breast Cancer
In this small open-label crossover trial, 14 breast cancer patients who had been on Tamoxifen at 20 or 40mg QD for at least 3 months were randomized to either Tamoxifen alone for 28 days, or Tamoxifen plus Green tea Extract for 14 days, followed by crossover. Green Tea Extract was dosed at 1000mg (with 150mg EGCG) BID, a dose roughly equivalent to 5 to 6 cups of green tea daily. Patients with genetic variations in CYP2D6 were excluded.
Endoxifen AUC during GTE supplementation was no different from that during tamoxifen monotherapy (p=0.92). There was also no difference in endoxifen Cmax or Ctrough during the combination or monotherapy periods (p=0.77). Likewise, the AUC, Cmax and Ctrough for Tamoxifen were no different during GTE supplementation compared to drug monotherapy (p=0.44, p=0.64, and p=0.34 respectively).
This small trial may give a measure of reassurance to people with breast cancer who wish to combine Green tea supplements and Tamoxifen.
Citation:
Braal CL, Hussaarts KGAM, Seuren L, et al. Influence of green tea consumption on endoxifen steady-state concentration in breast cancer patients treated with tamoxifen [published online ahead of print, 2020 Aug 16]. Breast Cancer Res Treat. 2020; 10.1007/s10549-020-05829-6.
Link: