Wikipedia says melanoma. Yes to the doris day being his mom. I have to thank her for my disdain for celebrities. When I was a youngster in the mid 50’s living in Carmel CA, they were filming a movie there and I approached her for an autograph and she blew me off like a 3 week old salad(?) and from that point on, I have held celebrities in the same ranking as an outhouse. (I know some are nice folks but for an impressionable little kid, I was crushed. But thanks doris.)
And she was the Queen of Nice!