Gardasil Viewed by AAP as an Anti-Cancer Vaccine

I have posted a few notes in the past about Gardasil, a vaccine against HPV, and the rise of oral cancers as a result of HPV infection. Here are a couple of representative ones (see: Some Key Questions in Cytopathology That Require Immediate Answers; An estimated 7% of Population Carry Oral HPV; Oral Cancer Incidence to Rise Sharply). A recent article about the Gardasil vaccine did catch my attention in a particular way, however (see: 11-year-old boys should get HPV shot, docs say). Here is a an excerpt from it:

Boys 11 years and up should get Merck & Co's Gardasil vaccine to protect them against HPV infections, which can cause genital warts as well as oral, penile and anal cancers, the nation's largest group of pediatricians said Monday. "What we are hoping will come out of this is that we can push this as a cancer vaccine," said Dr. Michael Brady of the American Academy of Pediatrics (AAP). "We now have the ability to interrupt the transmission and the development of cancer." The new statement leans on recommendations released last year by U.S. vaccine advisers and updates the previous stance of the AAP, which until now had only backed routine vaccination for girls....It's estimated that HPV types 16 and 18 are responsible for 7,000 cases of cancer in men every year in the U.S. and 15,000 cases in women, most of them cervical cancers. Clinical studies show HPV vaccines shield boys against genital warts and anal cancer, although the protection isn't complete. Vaccinating boys is also likely to protect women indirectly by preventing them from catching the viruses in the first place, the AAP says.

I never conceptualized Gardasil as a vaccine against cancer although it clearly can function in this way. Perhaps my problem was that I was having trouble making the leap from a vaccine that prevents a viral infection and the virus acting as the etiologic agent that causes the cancer. Just out of curiosity, I googled the term cancer vaccine and turned up a fact sheet from the National Cancer Institute (see: Cancer Vaccines). Here are two key quote from it:

The U.S. Food and Drug Administration (FDA) has approved two types of vaccines to prevent cancer: vaccines against the hepatitis B virus, which can cause liver cancer, and vaccines against human papillomavirus types 16 and 18, which are responsible for about 70 percent of cervical cancer cases. The FDA has approved one cancer treatment vaccine for certain men with metastatic prostate cancer.

[and]

Cancer vaccines are medicines that belong to a class of substances known as biological response modifiers. Biological response modifiers work by stimulating or restoring the immune system’s ability to fight infections and disease. There are two broad types of cancer vaccines:

• Preventive (or prophylactic) which are intended to prevent cancer from developing in healthy people; and
• Treatment (or therapeutic) which are intended to treat an existing cancer by strengthening the body’s natural defenses against the cancer.

So now we all have an understanding of the difference between a prophylactic and a therapeutic vaccine. Gardasil falls into the former category. I certainly have learned something from this exercise.