Psychologists and psychiatrists are prevented by their professional codes of conduct from giving a diagnosis for someone who's not under their personal care.

Since I'm neither of those things, I will go ahead and speculate (as a layperson) that your spouse is still in deep emotional shock and has gotten stuck in the denial stage — talking to doctors or getting treatment would mean admitting to himself that this is real and he has cancer, so he's trying to hold that off and pretend he can keep on going with his pre-cancer life.

Perhaps meeting up for coffee with other local PC patients would help him accept his new situation, but he'd probably resist joining a support group too. Nobody can help him until he's ready to accept help.