A larger percentage of oropharyngeal cancers might be related to human papillomavirus (HPV) than previously thought. The Centers for Disease Control and Prevention (CDC) reports that in a large sample of invasive oropharyngeal squamous cell carcinomas, 72% were positive for HPV and 62% were positive for high-risk HPV types 16 and 18, which are covered by the 2 commercially available vaccines (Gardasil, Merck & Co.;Cervarix, GlaxoSmithKline).
On the basis of these data, the CDC researchers suggest that vaccines could prevent most oropharyngeal cancers in the United States.
The vaccines are marketed mainly for the prevention of cervical cancer, but there is hope, and some evidence, that the vaccines might also protect against oropharyngeal cancer. For example, last year, the Costa Rica HPV Vaccine Trial found that the Cervarix vaccine reduced oral HPV infections in women by more than 90%.
However, the effect of the vaccines could vary by demographic factors; HPV prevalence differed by sex and race/ethnicity, the researchers note.
In their study, Martin Steinau, PhD, senior scientist at the CDC, and colleagues report that the current global incidence of oropharyngeal cancers is estimated to be 85,000 annually, although there is considerable geographic variation. In the United States, there are about 12,000 new cases diagnosed every year, and most are classified histologically as squamous cell carcinoma (OPSCC).
The retrospective analysis was published in the May issue of Emerging Infectious Diseases.
Dr. Steinau and colleagues sought to determine prevalence of HPV types detected in oropharyngeal cancers in the American population, and to establish a prevaccine baseline for monitoring the impact of vaccination.
They examined oropharyngeal tumors from 588 patients.
HPV was detected in 403 of the 557 patients with OPSCC (72.4%), and 396 (71.1%) were positive for only 1 or no high-risk types. A single HPV type was detected in 68.4% of cases, and 3.9% of samples contained 2 types. In 7 cases, only low-risk HPV types were detected. High-risk HPV16 was present in 337 (60.5%) cases, HPV18 was present in 14 (2.5%) cases, and 331 (59.4%) cases were exclusively positive for these 2 types.
Other high-risk types, including HPV31, 33, 35, 39, 45, and 52, were found at low frequency, the researchers point out.
There were differences in prevalence based on sex and race/ethnicity. The prevalence of the high-risk HPV16 and HPV18 was lower in women than in men (53%vs 66%), and in non-Hispanic black than other racial/ethnic groups (31% vs 68% to 80%).
When the researchers conducted a multivariate analysis for high-risk HPV, only race/ethnicity emerged as a significant independent factor (P = .003). The odds for high-risk HPV infections were significantly higher for all other race groups than for non-Hispanic black patients (P < .001).
When only HPV16/18 detection was considered, there were significant differences between those infected and those not infected for sex (P = .009) and race/ethnicity (P < .001), but not for age (P = .063).
“Future assessments are needed to monitor general prevalence and possible type-specific shifts,” the researchers conclude. “Data from the present and future studies will provide a baseline for early assessment of vaccine effects.”
This project was supported in part by CDC grants and federal funds for Residual Tissue Repositories from the National Cancer Institute SEER Population-based Registry Program, National Institutes of Health, Department of Health and Human Services. Coauthor Brenda Y. Hernandez reports receiving consultation and speaker fees from Merck and Co.
* This news story was resourced by the Oral Cancer Foundation, and vetted for appropriateness and accuracy.