"Did I insult your intelligence?"
You did not. You asked whether I had heard of anal cancer, which indeed I have. As that is not the norm, I explained why. And no, you couldn't insult my intelligence, my IQ is above 150 and I went to university myself. I'm pretty self-assured, so no need to apologize.
"Anal cancer, does occur because one engages in homosexual encounters."
Actually not. It does occur because of b*ttsex or autoerotic stimulation of the rectum. And that's all I'm saying: From a purely medical standpoint that distinction is relevant. Observations need to be empirically based, otherwise it's junk science.
HPV, specifically types 16 & 18 are considered likely culprits for anal cancer. There's a successful vaccine, recommended for girls, to prevent these types which are known to cause cervical cancer. It's hoped it might be useful in males as well.