According to a new report published by the Centers for Disease Control and Prevention (CDC), oropharyngeal squamous cell carcinoma (SCC), a cancer of the throat, has replaced cervical carcinoma as the cancer most commonly associated with human papillomavirus (HPV).
Human papillomavirus, the most commonly sexually transmitted infection in the United States, is a known cause of cervical cancer and some types of oropharyngeal, vaginal, vulvar, penile, and anal cancers. According to the CDC report, research indicates that around 90% of new cervical HPV infections clear or become undetectable within 2 years, and those that remain take decades to progress to invasive cervical cancer. Far less research has been done regarding the carcinogenic progression of HPV at other anatomical sites.
The CDC analyzed data covering 97.8% of the US population for all years from 1999 to 2015, using population-based cancer registries participating in the CDC's National Program of Cancer Registries and the National Cancer Institute's Surveillance, Epidemiology, and End Results program. They found that over the course of this 16-year period, the number of new cases of HPV-associated cancer increased from 30,115 to 43,371.
Over this time span, the frequency of different types of HPV-linked cancer also changed. In 1999, cervical carcinoma was the most common HPV-associated cancer, with 3,750 more cases of cervical carcinoma than of oropharyngeal SCC. From 1999 to 2015, however, cervical carcinoma rates decreased by 1.6% per year. In contrast, oropharyngeal SCC rates increased by 2.7% per year among men and by 0.8% per year among women. By 2015, there were 7,129 more cases of oropharyngeal SCC (18,917 cases) than of cervical carcinoma (11,788 cases).
During this time span, HPV-linked anal SCC rates also increased by 2.1% per year among men and by 2.9% among women, as did vulvar SCC rates (1.3%). Penile SCC rates remained stable, and vaginal SCC rates decreased by 0.6% per year. The CDC report suggests that changing sexual behaviors could be contributing to the increase in oropharyngeal and anal cancers, as unprotected oral sex and receptive anal sex are risk factors for HPV infection.
HPV vaccination was included in the routine immunization program in the United States, starting in 2006 for girls and in 2011 for boys, and it is recommended for all children between the ages of 11 and 12. The report notes that it may currently be too early to observe effects of the vaccination program on invasive cancers, but studies have shown reductions in cervical HPV infection, genital warts, and cervical precancers. Most cervical cancers can be prevented with a combination of HPV vaccination and regular screening among women aged 21 to 65. In a separate document with suggestions for clinicians, the CDC stresses the vaccine's importance, stating that it could prevent more than 90% of HPV-associated cancers from ever developing.
For More Information
Centers for Disease Control and Prevention (2018). Human papillomavirus (HPV). Available at: https://www.cdc.gov/hpv/hcp/hpv-important.html
Van Dyne EA, Henley SJ, Saraiya M, et al (2018). Trends in human papillomavirus–associated cancers — United States, 1999–2015. MMWR Morb Mortal Wkly Rep, 67:918-924. DOI:10.15585/mmwr.mm6733a2
Image credit: Markus Schober and Elaine Fuchs, The Rockefeller University. Courtesy of the National Institutes of Health