Welcome to the forum. I have been expecting your question --- if not from you, from someone.
It's nice to see the media attention to Mr. Douglas's HPV-related throat cancer; at least some of the news reports have been quite good, with mostly accurate information, such as the NY Times article by Anahad O'Connor, and the Bloomberg News article; I'm sure you can find them on line. This has also been discussed quite a bit on this forum over the past couple of years. The threads below summarize some of the key information; and as you'll see, one of them has links to still other threads as well.
http://www.medhelp.org/posts/STDs/HPV-and-oral-sex/show/1515473
http://www.medhelp.org/posts/STDs/Oral-HPV-Cancer-Risk/show/1512873
Some of the main take-home points are these: Only a single HPV strain, HPV-16, has been associated with oral cancers. Only some oral cancers are caused by HPV-16, in particular those of the tonsils and back of the throat. There are only several thousand such cancers per year in the entire US -- a rare problem in a country of over 300 million -- far less common than most serious cancers (breast, lung, colon, prostate, etc). The large majority of HPV infections, including HPV-16 (whether genital, oral, or elsewhere) clear up without ever causing cancer. Some oral HPV-16 cases probably don't come from oral sex. Stopping oral sex, even on partners known to have past or current genital HPV, probably would make little or no difference in the risk of such cancers -- but even if it would, it's simply not practical to expect anyone to avoid oral sex on this basis. The cancers that in theory might result are just too rare to be a serious concern.
For now, I would emphasize the importance of vaccination (both males and females) with Gardasil, the vaccine that prevents infection with 4 HPV types, including HPV-16 -- ideally before becoming sexually active at all, but any time up to age 26. Although it isn't yet proved that immunization will prevent HPV-16-related oral cancers, probably it will.
I hope this information has been helpful -- and most important, that it has reduced your concern about this issue. Best wishes-- HHH, MD