A vaccine to protect against the most dangerous strains of human papillomavirus (HPV), which cause almost all cervical cancers, as well as many cases of other cancers and genital warts in both sexes, won the approval of the U.S. Food and Drug Administration nearly nine years ago. The Centers for Disease Control and Prevention now recommends that all boys and girls aged 11 or 12 receive the shots. Vaccination campaigns, aimed largely at girls and women, have fallen short of expectations. By 2013 just over half of U.S. females aged 13 to 17 had received at least one dose of either the Gardasil or Cervarix vaccine. For males, that figure was a disappointing 35 percent. Now head and neck cancers associated with the virus are on the rise, leading some experts to recommend that a gender-neutral or male-centric approach might be more effective.
HPV is the most prevalent sexually transmitted disease in the U.S. and worldwide, infecting just about all men and women at some point in their lives. Although most people clear the virus naturally, persistent infections with some strains can lead to cancer—usually cervical or oropharyngeal (affecting the back of the throat, tonsils and back of the tongue). HPV-associated cancers make up 3.3 percent of all cancer cases among women and 2 percent of all such cases among men annually in the latest available figures, yet the incidence of virally instigated oropharyngeal and anal cancers is increasing.
Ohio State University medical oncologist and epidemiologist Maura Gillison has studied men with oropharyngeal cancer in three different decades. She and other colleagues first noticed an odd shift in patient profiles in the late 1990s: younger men were showing up in her clinic, often with no significant history of smoking or heavy drinking, which are risk factors for head and neck cancers. She later found that whereas from 1984 to 1989 in the U.S. only 16 percent of oropharyngeal cancers tested positive for HPV, by 2005 that figure had skyrocketed to 73 percent. By 2020 experts project that such cancer diagnoses will exceed those for cervical cancer in the U.S., shifting the burden of HPV-associated cancers from women to men. Gillison reported these findings in October 2014 at the annual ScienceWriters meeting.
Based on these data, Gillison thinks that the female-centric approach to HPV-related cancers in the U.S. should switch to focus on both men and women. Nobel laureate Harald zur Hausen, who discovered 30 years ago that HPV causes cervical cancer, has gone further, saying that males should get the vaccine if only one sex were the focus. The vaccine is currently voluntary in most U.S. states, and only a smattering of vaccination coverage campaigns exist, such as those launched by the New York City Department of Health and the Minnesota Department of Health in the past year. Public health messages and even research literature often fail to mention male vaccination prominently or at all. Unfounded fear of vaccines and claims that the HPV shots would provoke early teen sexuality have hindered efforts to vaccinate broadly in much of the U.S.
No data exist to prove that the vaccines protect against HPV-positive oropharyngeal cancer. But such coverage is probable given that the same strains that cause most cervical, vaginal and vulval cancers also cause most head and neck cancers. If a shift in public health policy were to result in an increase in male vaccinations, experts say, at the very least rates of females' HPV-associated cancers would decrease as a result of fewer infections acquired from men. And the rise in HPV-associated cancers in men would most likely decelerate, plateau or even reverse. A win for all of us.
FURTHER READINGS AND CITATIONS ScientificAmerican.com/mar2015/advances