From my perspective, that's actually a reasonable (or at least understandable) comment. "look good" means you're still energetic & smiling. Take it as a compliment. To some people, cancer means you're dying tomorrow. In terms of prostate cancer being "the good one".... badly expressed, but that's possibly someone who has at least looked into prostate cancer & they understand that it's one of the slowest-growing cancers. That's what makes it "the good one".

Here's my thing... I feel lucky that it's prostate cancer. If it was bladder cancer or lung cancer or something... I can't just say "Meh... take it out". But with prostate cancer I can.
That would also be true if it was brain cancer. That can be removed with no effect, because I work for local government.