HPV-Associated Cancers on Rise in US

Nick Mulcahy

July 07, 2016

The number of cancers associated with the human papillomavirus (HPV) has increased in the United States in recent years, according to a new report from the Centers for Disease Control and Prevention (CDC).

HPV-associated malignancies include cervical, vulvar, vaginal, penile, oropharyngeal, anal, and rectal cancers.

There was an overall increase in HPV-associated cancer incidence, from 10.8 per 100,000 persons during the period 2004-2008 to 11.7 per 100,000 persons during 2008-2012.

In terms of the total cases, each year during 2008-2012, an average of 38,793 HPV-associated cancers were diagnosed.

This is an increase from 2004-2008, when an average of 33,369 HPV-associated cancer cases were diagnosed each year.

The new study was published online July 7 in the Morbidity and Mortality Weekly Report.

The most common of these cancers during 2008-2012 were cervical carcinomas (annual average, 11,771) and oropharyngeal squamous cell carcinomas (annual average, 15,738), which mostly occurred among males (annual average, 12,638).

As clinicians know, not all of these cancers are caused by HPV infection; for example, although oropharyngeal cancer is an HPV-associated cancer, not all patients with oropharyngeal cancer are HPV-positive.

Nevertheless, the CDC says that the above list of cancers is indeed heavily related to HPV infection. Overall, most HPV-associated cancers are also attributable to HPV. Specifically, 79% of these cancers are attributable to HPV, the agency says, citing other research.

The CDC estimates that approximately 30,700 new cancer cases annually were attributable to HPV during the period 2008-2012.

The estimate was necessary because cancer registries, which were a source of the study data, do not routinely collect information on the presence of HPV DNA in cancer tissues.

Notably, most of the new cancers from 2008-2012 are related to HPV types that are covered by vaccines, according to the report's authors, led by Laura J. Viens, MD, of the Division of Cancer Prevention and Control.

They point out that "HPV vaccination can prevent infection with HPV types that cause cancer at cervical and other sites," including the anus. "Vaccines are available for HPV types 16 and 18, which cause 63% of all HPV-associated cancers in the United States, and for HPV types 31, 33, 45, 52, and 58, which cause an additional 10%," the authors assert.

"Increasing vaccination coverage could decrease the cancer incidence," the authors summarize.

 
Increasing vaccination coverage could decrease the cancer incidence.
 

The CDC team spells out just how much cancer might be prevented by HPV vaccination.

Of the 30,700 new cancers attributable to HPV during 2008-2012, the majority (80%) were attributable to HPV types 16 and 18. These can be prevented by the bivalent, quadrivalent, and nine- valent HPV vaccines. A further 12% were attributable to the five additional HPV types (31, 33, 45, 52, 58), which can be prevented by the nine-valent HPV vaccine.

The study authors say that vaccination programs can lower the prevalence of HPV infections.

For example, they observe that in high-income countries, HPV vaccination programs have had a population-level effect that includes reductions in vaccine type prevalence and rates of anogenital warts. Most of these warts are caused by HPV types 6 and 11, both of which are targeted by the quadrivalent and nine-valent HPV vaccines.

To conduct the study, the CDC used data from population-based cancer registries that participate in the CDC's National Program of Cancer Registries and the National Cancer Institute's Surveillance, Epidemiology, and End Results Program. Criteria for high-quality data were met for all years from 2008 to 2012.

The authors have disclosed no relevant financial relationships.

MMWR Morb Mortal Wkly Rep. 2016;65:661-666. Full text

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