The Anal Cancer Foundation recommends everyone who had this cancer get the HPV vaccination regardless of age. Some insurance covers it up to age 45, but I'm 79 so I paid out of pocket, even though there was no obvious sign of any lingering virus. It may be like the herpes virus, which hides until something stimulates it. Statistically, having had one HPV virus cancer actually greatly increases my risk of one of 8 more HPV caused cancers, or a new anal cancer. I can only hope that the vaccine helped, because it wasn't cheap.