Oh gosh, it is impossible really for any of us to diagnose what the lump is in your dog's ear. It could be anything. It probably ISN'T cancer...but you really need to take him in to the vet to get this seen as soon as you can. (Same protocol with ANY weird lump, anywhere.)
I am guessing it could possibly be a haematoma?? A blood-filled swelling. Dogs' ears are common sites for these.
But of course, I cannot tell you. Only the vet can.