I had a colonoscopy and pelvic ct 6 months ago for ibs , all clear. would these tests have detected anal cancer? i have hx of genital low risk hpv.

Very unlikely: These tests would not be likely to detect anal cancer. If you have a bump on or near your anus, pain, or anal bleeding, see a doctor. Without those, the chance of anal cancer is near zero if you have not been anally penetrated by another man. Anal cancer is quite rare in males, with only about 3,000 cases per year in the US, mostly in gay men. But ask your MD for exam if still uncertain.

Anal cancer: The colonoscopist would inspect and examine your anus before inserting the colonoscope and would have been able to detect abnormalities of the anus at that time. That is the way anal cancer would be suspected and then diagnosed by biopsy.

HPV/CA/colonoscopy: Yes it should detect cancer of the colon; rectal/anal lesions should have been visualized as well. HPV type 16 may be associated with anal cancer . If you are low risk HPV, it is unlikely . Get vaccinated against HPV 16 if you are not positive ( even if + for others) to prevent the cancers https://www.cancer.gov/about-cancer/causes-prevention/risk/infectious-agents/hpv-fact-sheet