He’s probably projecting now that he’s (presumably) gotten his life together and now has the mindset of “All drugs are bad and will **** your life up!” He may be terrified of his kid going down the same path as him. Maybe calmly let him know it’s legal and for medical purposes, you don’t intend to abuse it or do any other drugs, and you won’t get in trouble for it. If he’s still unreasonable, just agree to disagree and avoid doing it around him. Sorry you had a largely absent father in your childhood, and so sorry that you’re going through potentially terminal cancer. That’s pretty ******* heavy to deal with. Stay positive, continue with your treatments, and hopefully you’ll have an amazing outcome and beat this ❤️

Stay strong and focus on the positive, you have my support. I think Dad should be more worried about your medical condition and it's outcome than what you are doing to seek relief (from the symptoms or the side effects of chemo and radiation, which I hear can be rough).

I hope you meant "treat" as in pain reliever/anxiety reducer, and not actually attempting to cure cancer solely through canibus usage