How Does Smoking Marijuana Affect Brain Tumor Treatment?

I just found out that my 37 year old daughter found out a few months ago that she has a brain tumor about the size of a quarter. Cancer is famous on her dad side of the family. She has lost her grand mother, grand father, dad, and aunts. She has been taking some kind of medication to help her with nausea from the medication she was taking to possible dissolve the tumor. Is there a possibility that this tumor will dissolve? I know for a fact that she smokes marijuana and from my standing point I can't see how that would help matters. Any info will help me understand and what to expect. Thank you.