With the alarming rise in the rate of oropharyngeal cancer among men being linked to the human papillomavirus (HPV), the U.S. Centers for Disease Control and Prevention (CDC) is considering whether to also recommend the HPV vaccine for boys.
Two vaccines (Cervarix and Gardasil) are currently available to protect females against the HPV types that cause most cervical cancers. The CDC currently recommends both for 11- and 12-year-old girls and for females 13 through 26 years old who did not get the three recommended doses when they were younger.
The number of HPV-related oral cancers cases among men in the U.S. is increasing so quickly they could surpass the number of cases of cervical cancers in women by 2020, according to research presented last month at the American Society of Clinical Oncology annual meeting in Chicago.
Between 1984 and 1989, only 16% of oropharyngeal cancers were linked to HPV. But by 2000-2004, HPV was related to 75% of oropharyngeal cancers, according to the National Cancer Institute (NCI). In 2010, the institute estimated that there were 12,660 cases of oropharyngeal cancer, resulting in 2,410 deaths. About half of those cases were among males and at least 75% were caused by HPV, according to NCI researchers.
Several studies and oral cancer specialists have attributed the sharp rise in HPV-positive oropharyngeal cancers to an increasing prevalence of oral sex among young people.
For the past few years, the CDC's Advisory Committee on Immunization Practices (ACIP) has been mulling whether to recommend the HPV vaccine for boys, as is now suggested for girls and young women to prevent cervical cancer.
At the ACIP's June meeting in Atlanta, the panel again discussed the issue, including the cost-effectiveness for male vaccination. The 15-member group did not vote on the matter, but it is expected to do so when it meets again in October.
More research needed?
While some panel members think the vaccine should be recommended for boys now, others say more definitive research is needed first.
HPV cancers in males account for 7,000 cases a year, according to ACIP member Mark H. Sawyer, MD, a professor of pediatrics and an infectious disease specialist at the University of California, San Diego. He agrees with some oral cancer specialists who feel that the vaccine should be given to boys now, given the alarming rise in HPV-related oral cancers among males.
— Dong Moon Shin, MD, Emory
"I think it's reasonable to recommend the vaccine for boys," Dr. Sawyer told DrBicuspid.com. "Giving them the vaccine before they become sexually active makes sense. Children and parents could get used to the idea that you go in and get a series of vaccines for adolescents."
Dr. Sawyer said there was a "mixed point of view" during last month's meeting regarding recommending the vaccine for boys.
CDC researcher Eileen Dunne, MD, MPH, told DrBicuspid.com that most members of the ACIP's HPV working group favor routine vaccination of all males when they become sexually active.
Dong Moon Shin, MD, a professor of hematology and medical oncology at the Winship Cancer Center of Emory University in Atlanta, agrees that the time has come to vaccinate both boys and girls for HPV.
"This vaccination should be given to young boys and girls before they become sexually active," he told DrBicuspid.com. "I think it is critically important to prevent HPV infections, which can develop into cancer."
The prevalence of oropharyngeal cancer has significantly increased annually during the last decade, Dr. Shin noted.
"We have learned that it is clearly associated with the HPV virus, particularly types 16 and 18, which is exactly the same virus that causes cervical cancer among women," he noted.
However, while HPV infection is now quite common, it rarely develops into cancer, Dr. Shin added.
"We still don't know what causes the virus infection to transform to cancer, so therefore we believe multiple molecular mechanisms should be studied," he said. "We need more study, but we don't need to wait that long to understand the carcinogenesis process, and the vaccine should be given as more studies are done."
Benefits vs. side effects
Aimee Kreimer, PhD, an expert in head and neck cancer at the National Cancer Institute who gave a presentation at the ACIP meeting, says more research is needed before routine HPV vaccinations are given to young people. While the proportion of HPV-positive oropharyngeal cancer is increasing, the overall numbers are still rare relative to other cancers such as breast and prostate cancers, she noted.
"When considering the vaccine, we can't just think about the number of cases attributed to the HPV virus because, in fact, direct evidence that the vaccine will work to prevent these cancers is lacking," Kreimer told DrBicuspid.com. "This is a very safe vaccine, but when you start to vaccinate millions of people, it is important to balance the benefit of the cancer prevention with possible side effects of the vaccine."
While Kreimer prefers to see evidence of the vaccine's efficacy, she is cautiously hopeful about its prophylactic value.
"If the vaccine were given to men, I would be optimistic that it would reduce the rates of oropharyngeal cancer, but I still like to base decisions on hard data," she noted. "We want to be sure the balance tips the scales toward societal benefit in terms of cancer prevention."
Sol Silverman Jr., DDS, a professor of oral medicine in the University of California, San Francisco School of Dentistry, concurs with Kreimer's assessment that more research is needed before the HPV vaccine is recommended for boys as well as girls.
"It's not evidence-based, but it's obvious that boys who are HPV-negative, if they were vaccinated, probably in the long run it would, to some degree, reduce the risk of transmission of the virus," he said in a recent interview with DrBicuspid.com. "When you have these public health issues that have personal priorities, they're expensive and you have to have pretty good evidence that it's going to be helpful."