SEATTLE – Efforts to promote vaccination of boys against human papillomavirus may be more successful if they de-emphasize infection-related outcomes that make parents uncomfortable because of their sexual associations, according to a study of 158 parents of boys.

Surveyed parents were less likely to intend to vaccinate their son if they ranked anal cancer or oropharyngeal cancer as the most severe possible outcome of human papillomavirus (HPV) infection, investigators reported at the annual meeting of the Society for Adolescent Health and Medicine.

Comments made in focus groups suggested that these cancers elicited negative emotions: stigma in the case of anal cancer because it was associated with anal sex and homosexuality, and anxiety in the case of oropharyngeal cancer because it was associated with oral sex.

"Parents seemed to dwell on the sexual transmission of HPV," commented lead investigator Abigail C. Lees, a research assistant in the pediatrics department at the University of North Carolina, Chapel Hill.

"HPV awareness campaigns should decrease emphasis on outcomes that elicited either stigma associated with anal cancer or increased anxiety associated with oral cancer, and instead focus on prevalence," she recommended. "Furthermore, the parental preoccupation with the sexual transmission of HPV could be entirely avoided by vaccinating children at younger ages, when parents are less likely to associate stigmas or anxiety with their child’s behavior and the vaccine."

A quarter of the HPV-associated cancers that occurred in 2009 were in males, according to Ms. Lees. The quadrivalent HPV vaccine is now licensed for prevention of genital warts and anal cancer in both males and females, as well as for prevention of cervical, vulvar, and vaginal cancer in females.

To assess parental knowledge about male HPV outcomes and attitudes about vaccinating sons, the investigators recruited to their study parents of boys aged 11-17 years from a pediatric clinic, university listservs, craigslist, and other venues.

They completed surveys asking about perceived susceptibility (at least a 40% chance) of their son experiencing HPV infection and its outcomes, and perceived severity of the outcomes. They also participated in single-sex focus groups, conducted separately in English and Spanish.

The majority of the parents, 72%, were the boy’s mother. By race/ethnicity, 54% were white, 23% were black, 15% were Hispanic, and the rest were other. About a third had a high school diploma or less education. Slightly more than half were currently married. And 61% also had a daughter.

"Overall, parents believed their sons to have a low susceptibility to HPV infection and its outcomes," Ms. Lees reported. Just 22% thought their son was susceptible to infection. And smaller proportions thought he was susceptible to genital warts (18%), oropharyngeal cancer (11%), anal cancer (9%), and penile cancer (9%).

However, 82% of parents believed the consequence of HPV infection in their son would be severe; of these, 31% ranked penile cancer as the most severe possible outcome, 30% oropharyngeal cancer, 23% anal cancer, and 16% genital warts.

Eighty-three percent of parents indicated that they intended to vaccinate their sons against HPV. In a multivariate analysis, parents were more likely to intend to do so if they were older (odds ratio 1.14) and believed that the consequences of HPV infection could be severe (OR 9.94).

On the other hand, they were less likely to intend to vaccinate if they were more educated (OR 0.62). And there were trends whereby they were less likely to intend to do so if they ranked anal cancer or oropharyngeal cancer as the most severe possible outcome (OR 0.25 and 0.67, respectively).

"The most striking finding from our focus groups was that parents had very limited knowledge of HPV infection in males, despite an awareness of HPV in females," commented Ms. Lees. For example, parents were often unaware that HPV infection pertained to boys.

Their comments also provided some insight into why high rankings of certain HPV-related outcomes might have been associated with lower odds of intending to vaccinate. "Parents responded to the sexual nature of transmission, in particular, in focus groups, which revealed parental stigmatization of anal cancer by association with homosexuality among males," she noted.

In addition, "parents expressed an anxiety associated with oral sex practices they perceived youth to be engaging in," Ms. Lees elaborated. "Parents alluded to the frequency of oral sex among youth" and expressed "concerns that youth believe oral sex can be used to avoid infidelity, is safer than intercourse, and preserves their virginity."

Taken together, the study’s findings should help to inform provider and public health efforts to increase uptake of the HPV vaccine among boys, she concluded.

Ms. Lees reported that the investigators received grant support from Merck to conduct the study.

Sexual Associations of HPV May Be Barrier to Vaccinating Boys