HPV caused anal cancer for me and Farrah Fawcett.
Same strain/s cause cervical cancer in women.
I was a stage IIIb, so I had very aggressive treatment.
You don't mention if your partner has finished treatment, so I'm assuming she is still ill with radiation and chemo....
Her doctors will be glad to counsel you. But as cancer is not contagious, your fear of penal cancer seems unfounded.
HPV can be passed. Everyone has it...but there are many strands of this mysterious virus...some people are carriers only, while others become ill.
If you are in right age range...get vaccinated. See a doctor about your concerns.
Lots of info on HPV in wiki...and if you google it...will be swamped!
it is possible but exptremly unlikely..... also a chance of getting anal cancer from HPV....