Does anyone take Milk Thistle? r/o

I read that milk thistle is a liver cleanser and can benefit those who have breast cancer. I am thinking since my mother has liver mets of having her ask her oncologist about it.

Does anyone currently use milk thistle? If so, what dosages do you take?

Update: My mom took her CAT scan and everything is good, the liver tumors are very tiny. She just finished a clinical trial (a new drug for boosting your hem. count) and is finishing up on taxotere (sp?. Her oncologist may give her a break from all the chemo for a few months. Thank G-d she feels good!