Yikes, this seems to be insensitive doctor week here at WhatNext. As soon as he walks into the room, tell him that you've been in his care for ____ . That you have some questions you would like answered and his hit and run modus operandi is offensive to you. How he responds will guide your next steps. If he stays, and answers your questions, and you can talk to him about a collaborative relationship, give him a few more visits.
If he is brusk, leaves, offend, etc then it's time to find a doctor you feel comfortable working with. When you do switch to that doctor and let your current oncologist and when you leave, let the oncology know exactly why you decided to do so.