For non-functional pituitary macroadenomas, how effective has cabergoline been in reducing tumor size or preventing the need for surgery?  

There is some literature suggesting that a modest effect is seen in preventing tumor regrowth in previously operated NFPA (Treatment of clinically nonfunctioning pituitary adenomas with dopamine agonists - PubMed). The data on primary therapy is less convincing. Topic reviewed recently in Pharmacolo...