[donocco]

I just saw that myself about possible estrogen action. I wasnt gpong to anwer until I did some research. Its all confusing because it seems milk thistle is a weak estrogen which could actually be beneficial by blocking the effect of stronger estrogensBut so is Genistein found in soy very weak but this "weak estrogen can stimulate breast cancer growth in rats.
If it really does have a preventive action against brain mets the benefits might well outway the risks but I would hesitate to confirm this based on one study. Talk with the oncologist first. Herbs are complex because they contain many chemical constituants