However, in a certain set of HPV-positive tumors the viral oncogene is not incorporated into the host cell's DNA and in some it is -- so what is going on is not clearly known -- these again may turn out to be sub-sets of the general HPV+ tumor.

I read an interesting paper which refers to what Brian mentions -- some people seem to be able to rid themselves of the virus -- the study found that ~25% of the women with HPV+ pre-cancerous lesions which were scheduled for surgery (often cryosurgery) had no sign of the lesions when they came in for the treatment. And certainly not everyone + for HPV-16 gets cervical cancer or oral cancer.

Still much to learn...

Gail