Gift,
I love your screen name. I believe the association is with the caffeine in coffee and tea, which is thought to have estrogenic effects. Here is a link to another thread where Rich66 posted some research:
http://her2support.org/vbulletin/sho...fee#post235360
Herbal teas are best to avoid caffeine, as even decaffinated coffee and tea contains some caffeine.
Best of luck with your treatment,
Hopeful