There's bias in this new piece and Gillison and I have discussed it. The correlation with HPV is the number of sexual partners not pot. One possible bias is people that have multiple sexual partners might also be people that at pot users or whatever. The study does not draw a link between pot and HPV, they could just as easily be non connected behaviors in people in the study. I think it would be fair to say that a long term pot user might also be a person who had many sexual relationships during those years as well. That is NOT the same as saying that the use of pot makes you more susceptible to HPV. When you get into small studies that look at behaviors and try to correlate them with disease progression it is a road full of potholes. This kind of bias has been obvious is eating studies and others.

please note this study also out recently

Smoking marijuana doesn't seem to cause oral cancer
By Helen Fields
4/14/05

Marijuana smoke, like tobacco smoke, contains many carcinogens. Researchers in Seattle looked at whether it increases the risk of oral cancer.
What the researchers wanted to know: Does smoking marijuana increase the risk for oral cancer?

What they did: The researchers used 407 people between 18 and 65 years old who lived in one of three counties around Puget Sound, in Washington State, and had been diagnosed with oral squamous cell carcinoma