The Shot that Stops Cancer

Although sexually-transmitted human papillomavirus (HPV) infections can cause certain cancers and genital warts in both men and women, the link between HPV infections and cervical cancer makes these viruses especially dangerous for women. For that reason, the CDC added the HPV vaccine to its schedule of recommended vaccines a few years ago. Today, girls and young women can receive an HPV vaccine to prevent infection with the viruses that cause 70% of all cervical cancers (ideally, a girl is vaccinated before she becomes sexually active).

In the past, the CDC has recommended the HPV vaccine only for girls and young women. Boys and young men, who (clearly) often pass on HPV to women, were not vaccinated. Earlier this year, however, the CDC changed a footnote in its HPV vaccine recommendations to include boys and young men.

The CDC's 2010 recommended immunization schedule rather mincingly states that "HPV4 [one of the HPV vaccines] may be administered in a 3-dose series to males aged 9 through 18 years to reduce their likelihood of acquiring genital warts," no doubt to persuade parents of boys that the HPV vaccine can directly benefit their sons. Vaccinating boys, however, also helps prevent cervical cancer in their future female sexual partners.

A recent study in Pediatrics by immunization expert Dr. Gary Freed found that about 11% of parents refuse some vaccines because of concerns that the vaccine might cause health problems or autism in their children. These vaccine safety concerns have been disproved by numerous studies but persist among some parents nonetheless.

I suspect that, in an era of frequent vaccine refusal by parents, the CDC and its advisory committee, ACIP, decided that it was easier to "sell" parents of boys on the HPV vaccine if they said that the vaccine protected their boys from genital warts than if they said that the vaccine would protect their sons' future girlfriends and wives from cancer.

When parents consider getting the HPV vaccine for their boys, perhaps they should ask themselves this: if you could take one small step to prevent cancer in someone else - wouldn't you?

Gender and Cancer Vaccines

A number of cancer vaccines are on the market or under investigation right now, many targeted to gender-specific cancers. Along with the FDA-approved Gardasil(TM) HPV vaccine, which can prevent certain types of cervical cancer, trials are underway on the prostate cancer vaccine GVAX(R), a breast cancer vaccine, and another cervical cancer vaccine.

One important difference between all these vaccines is that Gardasil is given before any cancer diagnosis, and the other vaccines under trial that I mentioned are given after a cancer diagnosis in addition to standard cancer treatment. These post-diagnosis vaccines seem to be the trend with cancer vaccines, despite the heavy marketing of Gardasil. These vaccines are designed to "retrain" the patient's immune system to respond more effectively to proteins associated with cancer cells. Some of these vaccines are developed using the patient's own cells, and other are not.

Two promising post-diagnosis vaccines under investigation that are not gender-specific target lung cancer (the most deadly cancer among both men and women) and cutaneous melanoma (which is more deadly among men than among women).

I'm curious about the gender differences between cancer vaccines. Do women respond more favorably than men to cancer vaccines, or vice versa? Are vaccines that use the patient's own cells more or less effective than those that don't? Are vaccines for gender-specific cancers, such as prostate and cervical cancer, more or less effective than vaccines for cancers that can strike both genders? There might be no patterns here, but if there are, it would be interesting to see how physiology, sociology, and other factors impact the effectiveness of these vaccines.