Only modern medicine will save his life if he does have a recurrence. Unfortunately belief in homeopathy and denial are strong emotions and not easily overcome. You can tell him people here have had recurrences and are still fighting fit if a little battle scarred. I've had two. The cancer has to cut be out and usually zapped to make sure it doesn't come back again. Letting the cancer run it's natural course (because alternative treatments won't stop it) will lead to an unpleasant demise. What can you do to get him to a doctor? The only thing I can think of is to show him how deeply concerned you are. Have a meltdown, show him that you are heartbroken and beg him to go for your sake. Ask him to see a cancer counsellor of some sort.

I wish you all the best.