My son has testicular cancer and is being treated for it right now. He had no symptoms from the tumor in his testicle. No pain, no lumps, and no soreness despite the tumor inside his testicle. The symptoms leading to his diagnosis were respiratory in nature because it had spread to his lungs and the lymph nodes in his stomach. I hope this is reassuring that your H's symptoms don't match.
Everything happens for a reason, maybe Dad needs to find that it isn't better out there, he needs to realize how good he had it here. Maybe he will find God and that is the most important thing when he finds Him he will know he is supposed to come home.
