Cervical cancer affects more than half a million women and causes more than a quarter of a million deaths each year globally. Almost all cervical cancers result from a human papillomavirus, or HPV, infection. HPV infections cause cancers in other parts of the body, too. But the latest HPV vaccine could prevent most infections -; and millions of cancers -; worldwide, according to an article by Cosette Wheeler, PhD, and her collaborators.
The article describing the HPV vaccine and strategies to overcome issues with its use was published online by the American Society of Clinical Oncology. ASCO shared a print of the article with the 30,000 attendees at its Annual Meeting this year. Annual Meeting attendees included top oncologists from around the country and the world. Wheeler is an international HPV expert, a University of New Mexico Regents' Professor and a member of The University of New Mexico Comprehensive Cancer Center. She and the other authors of the article served as expert panel members for the Primary Prevention of Cervical Cancer: ASCO Resource-Stratified Guideline.
The HPV vaccine could prevent up to 90 percent of HPV-related cancers worldwide, according to the article. The authors report that women in high-income countries or regions are far more likely to survive a cervical cancer diagnosis. But even within high-income countries, those women in lower-income regions get cervical cancer more frequently and fewer of them survive it. And, this disparity applies to other HPV-related cancers in women and men, including other genital cancers, anal cancers, and cancers of the mouth and throat.
The HPV vaccine can prevent HPV infection if the vaccine is given before exposure to any of the HPV types that the vaccine protects against. Different formulas of the HPV vaccine protect against different types of HPV. Only two types, HPV16 and HPV18, cause 70 percent or more of all invasive cervical cancers and all HPV vaccine formulas protect against these two. The nonavalent formula of the HPV vaccine is the most protective: it protects against HPV16, HPV18 and five other cancer-causing HPV types. As of June, 2017, only the nonavalent HPV vaccine is available in the United States.
Experts estimate that the nonavalent HPV vaccine could reduce HPV-related cancers worldwide by 90 percent or more if the entire global population received it. Several studies have shown the vaccine to be efficacious. Studies have also shown its benefits and its harms to be similar to many other vaccines that protect against infections.
Currently, though, global HPV vaccination rates are low. The vaccine must be given in two or three doses. This can prove difficult for teens and preteens who lack easy and affordable access to a clinic and who do not receive regular medical check-ups. The article suggests giving the HPV vaccine with other childhood vaccines as a critical strategy to lessen this burden. The article also cites studies that have shown two doses to be as protective as three doses if vaccination is started at a younger age. The United States Advisory Committee on Immunization Practices now recommends two doses of HPV vaccine for both boys and girls, but only if they receive their first HPV vaccine dose between ages 9 and 14. After a teen's fifteenth birthday, the Committee still recommends three HPV vaccine doses.
The article strongly recommends reaching out to parents, teachers, medical providers and other community members to encourage HPV vaccination among teens and preteens. Providers' support of using the HPV vaccine is linked to higher vaccination rates, the article states. The article goes on to say that providers' strong recommendation for HPV vaccination is therefore key to protecting global populations against HPV-related cancers.
"Cervical and other HPV-related cancers are preventable," says Wheeler. "We have the unprecedented opportunity to impact the global cancer burden and improve people's lives and health everywhere."