Source: National Cancer Institute
A bellwether moment in the history of cancer prevention came in 2006 when the Food and Drug Administration (FDA) approved the first vaccine to prevent cervical cancer. The vaccine, Gardasil, protects against the two primary cancer-causing, or oncogenic, types of the human papillomavirus (HPV)—HPV-16 and HPV-18. These types are responsible for more than 70 percent of cervical cancer cases worldwide. In 2009, the FDA approved a second HPV vaccine, Cervarix, which also targets HPV-16 and HPV-18.
Gardasil and Cervarix, vaccines that protect against the two primary cancer-causing types of the human papillomavirus (HPV), entail a three-shot regimen, with each dose delivered several months apart.
But what has transpired since these two vaccines received regulatory blessing in the United States has reaffirmed something that cancer and public health researchers have appreciated for some time: The translation of basic research to the clinic doesn’t end with FDA approval of a new drug or treatment. In many respects, FDA approval is just a beginning.
In March 2007, the CDC’s Advisory Committee on Immunization Practices (ACIP) gave its strongest recommendation for HPV vaccination for females ages 9 to 26, which is the FDA-approved indication for Gardasil. Cervarix is approved for females ages 10 to 25. Both vaccines entail a three-shot regimen, with the doses delivered several months apart. According to the most recent data, only 44 percent of adolescent girls 13 to 17 years of age have received at least one dose of the vaccine. Completion rates for the three-shot regimen are substantially lower, with only 27 percent of adolescent girls receiving all three doses.
“Uptake is low because of problems with policy, problems with clinical encounters, and problems with parents’ decisions,” said Dr. Noel Brewer of the University of North Carolina Gillings School of Global Public Health. These obstacles are by no means insurmountable, but addressing each obstacle will take time, patience, and research, say investigators working in this area. And a good bit of that research can be grouped into two categories: missed opportunities and teachable moments.
HPV Vaccines for Boys
Gardasil has also been approved by the FDA for use in boys. The initial approval in boys, in 2009, was for the prevention of genital warts because Gardasil, unlike Cervarix, also protects against two other HPV types—HPV-6 and HPV-11—that are the primary cause of genital warts.
But, in December 2010, the approval was expanded to include the prevention of anal cancer, another disease associated with HPV-16 and HPV-18 infection. Because the approval for boys is so recent, this article focuses only on the uptake of the HPV vaccines by females.
No vaccine has an uptake rate of 100 percent, although when vaccines are mandated, such as those required for school attendance, vaccination rates can reach 80 to 90 percent. Although there has been a flurry of legislative activity at the state level since Gardasil was approved in 2006, only Virginia and Washington, DC, require HPV vaccination for school entry, and Virginia’s law includes a provision that allows parents to opt out of the requirement.
Based on surveys that Dr. Brewer and his colleagues have conducted, concerns that HPV vaccination will encourage sexual activity seem to have had little to do with the lagging vaccination rates. Nor, he continued, has uptake of the vaccines been substantially affected by the antivaccine movement that was spurred by fears raised about the now-discredited links between autism and childhood vaccines.
In general, concerns about safety and other issues with vaccines “are not specific to the HPV vaccine,” said Dr. Gregory Zimet of the Indiana University Melvin and Bren Simon Cancer Center. “There is a general vaccine hesitancy that affects a lot of parents.”
The Power of Physician Recommendations
Factors affecting vaccination rates have “definitely been a mixed bag,” agreed Veronica Chollette, who oversees a portfolio of HPV vaccine-related research in NCI’s Division of Cancer Control and Population Sciences. Cultural issues, lack of awareness, and, initially, reimbursement issues that limited the amount of vaccine physicians were willing to keep in stock have all played a role, she noted.
Physician encounters have also had an effect in an entirely different way. In a study published last year, less than 60 percent of pediatricians reported that they strongly recommended HPV vaccination for their 11- to 12-year-old patients. Another study of women ages 19 to 26 showed that, among women whose doctors did not recommend HPV vaccination, only 5 percent were vaccinated. Among those who did receive a recommendation, 85 percent were vaccinated.
“Pediatricians and family physicians are missing a lot of opportunities when patients come in for office visits,” said Dr. Brewer. Part of the problem, he added, is a systemic issue: health care providers are not flagging the charts of patients who are eligible for the vaccines or using reminder systems in electronic medical records, for example.
Interactions with the health care system drop precipitously once kids reach adolescence, he continued. “So it’s a big deal to miss those chances.”
Sociocultural factors are also important to consider. A study conducted in Appalachia, for example, found that conservative religious beliefs and a mistrust of outside influences played a prominent role in the vaccines’ acceptability. Meanwhile, studies of college-age women have shown that, even when receipt of the initial HPV vaccine dose was similar among white and black women, completion rates for all three doses were substantially lower among black women.
The disparity is noteworthy, Chollette stressed, because black women and Hispanic women have significantly higher cervical cancer incidence and death rates than white women.
In some cases insurance status can affect vaccine uptake and adherence. But, because federal and state-level programs, such as the Vaccines for Children program, make the vaccines available for free or for a minimal charge to low-income children, it may not contribute as much to the disparities in vaccination rates, said Dr. Ruth Carlos of the University of Michigan Medical Center. In fact, a higher percentage of 13- to 17-year-old girls from families below the poverty line have received at least one dose of the vaccine compared with girls from families above the poverty line (52 percent versus 42 percent). Also, a provision in the federal health care reform law requires private insurers to cover all ACIP-recommended vaccines with no co-pay requirements.
It’s a complex problem, acknowledged Dr. Zimet. For example, based on studies he has done involving the hepatitis B vaccine, he explained, “practical obstacles, like transportation to the clinic and how many children the mom is taking care of at home” can have an impact, particularly on adherence to the three-shot regimen.
A variety of approaches are being tested to increase vaccination rates, many of which are focused on moments or interactions that can influence awareness and decision making. Drs. Zimet and Brewer lead initiatives in their respective states that are part of the national Cervical Cancer-Free America campaign. In North Carolina, Dr. Brewer said, they are focusing their efforts on school-located health centers, where many children already receive other vaccines.
Other studies and programs are testing whether social media and text messaging can be used as educational platforms and reminder systems for adolescents and women.
A Mother’s Attitude Is Key
For younger girls, the available data strongly indicate that a single factor heavily influences whether they get vaccinated: their mother. “The gateway to adoption of the vaccine[s] is through the parents,” Chollette stressed. In particular, she continued, mothers are the key. “The mother’s values play a prominent role in whether girls go to the doctor and get all three doses according to schedule.”
Dr. Carlos and her colleagues are attempting to use cancer screening appointments as “teachable moments” for mothers of adolescent girls. In two separate studies, women undergoing breast and cervical cancer screenings who have adolescent daughters will receive tailored information about cervical cancer and the HPV vaccines. The studies will test different means of providing the information, including using a Web-based platform, and vaccination rates will be tracked via electronic medical records.
“From a public health perspective, it makes perfect sense to target mothers who come in for cancer screening,” Dr. Carlos said. Women undergoing their own cancer screenings “may be more receptive to acting on educational information about HPV prevention,” she continued. “Part of what this study is doing is encouraging this receptivity after being screened, and using that to encourage them to get their daughters vaccinated. The message is: ‘You’ve done something to protect yourself against cancer, so why not protect your daughter against HPV?’”
This news story was resourced by the Oral Cancer Foundation, and vetted for appropriateness and accuracy.