Hello @lighthouse68. Unfortunately, there is just not enough research out there on cannabis and THC oils yet to have scientific information to share. However, when talking about using anything as a treatment for a diagnosed medical condition, it is always best advice to have your medical provider looped in on the discussion, especially if you are taking other medications and worried about how they will interact with one-another. I understand that discussing medical marijuana in any form with a provider can be a tricky conversation. @lighthouse68, if you don't mind sharing, what was the source that you came across that said it can shrink the tumors?