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Rising Rate of Mouth and Throat Cancers Caused by HPV

Oral cancers caused by oncogenic human papillomavirus (HPV) -- the same virus that causes cervical and anal cancer -- are increasing in prevalence, researchers reported in the October 3, 2011, advance online edition of the Journal of Clinical Oncology. The trend may be related to growing acceptance of oral sex and a decline in smoking, and suggests that young men as well as young women could benefit from routine HPV vaccination.

Anil Chaturvedi from the National Cancer Institute and colleagues analyzed trends in oropharyngeal (mouth and throat) cancers in the U.S. using data from the Surveillance, Epidemiology, and End Results (SEER) Program.

The researchers determined HPV status for individuals diagnosed with all 271 cases of oropharyngeal squamous cell carcinoma recorded during 1984-2004 in the 3 population-based cancer registries in the SEER Residual Tissue Repositories Program.

The study authors used polymerase chain reaction and genotyping (Inno-LiPA) assays to detect and classify HPV. Looking at HPV type 16, which is responsible for the largest proportion of HPV-related cancers, they measured HPV16 viral load and HPV16 mRNA expression, indicators of active viral replication.

Trends in HPV prevalence were estimated across 4 calendar periods. Observed HPV prevalence was re-weighted to all oropharyngeal cancer cases in the registries, to account for non-random selection and calculate incidence trends. Finally, multivariate analysis was used to compare survival of HPV positive and HPV negative individuals.

Results

• Overall prevalence of HPV in oropharyngeal cancers increased significantly over time regardless of the type of detection assay used.
• HPV prevalence by Inno-LiPA increased from 16% during 1984-1989 to 72% during 2000-2004.
• Interestingly, median survival was significantly longer for people with HPV positive compared with HPV negative oral cancers (131 vs 20 months, respectively; adjusted hazard ratio [HR] 0.31).
• Survival increased significantly across calendar periods for people with HPV positive cancers, but not for those without HPV infection.
• Population-level incidence of HPV positive oropharyngeal cancers increased by 225% from 1988 through 2004, from 0.8 to 2.6 per 100,000 person-years.
• HPV negative cancers declined by 50% during the same period, from 47% to 53%, or from 2.0 to 1.0 per 100,000 person-years.
• People with HPV positive oral cancers were significantly younger, more often male, and more likely to describe themselves as white or "other" race/ethnicity (vs black).

These findings led the study authors to conclude, "Increases in the population-level incidence and survival of oropharyngeal cancers in the United States since 1984 are caused by HPV infection."

"The rapidly growing burden of HPV positive [oropharyngeal cancers] in the United States has important public health and clinical implications," they elaborated in their discussion. "By 2020, the number of HPV positive [oropharyngeal cancers] is expected to surpass the number of cervical cancers, the focus of prophylactic HPV vaccination."

They estimated the numbers at 8700 oral cancers vs 7400 cervical cancers. Two vaccines are approved for preventing cancers caused by HPV types 16 and 18, GlaxoSmithKline's Cervarix and Merck's Gardasil; Gardasil also helps prevent genital warts caused by HPV 6 and 11. Routine vaccination is recommended for adolescent girl and young women, but not yet for young men, although studies have shown they can also benefit.

"[T]he rising burden of HPV positive [oropharyngeal cancers] argues for evaluation of the efficacy of vaccination to prevent oral HPV infections, particularly given the unavailability of screening for [oropharyngeal cancers]," they continued. "The high efficacy of HPV vaccines in preventing extracervical infections among women (eg, vagina and vulva) and penile and anal infections among men implies that efficacy may be comparable against oral HPV infections."

Investigator affiliations: Surveillance, Epidemiology, and End Results Program, National Cancer Institute, Rockville, MD; Cancer Research Center of Hawaii, Honolulu, HI; Ohio State University, Columbus, OH; University of Southern California at Los Angeles, Los Angeles, CA; University of California and Radiation Therapy Oncology Group Biospecimen Resource, San Francisco, CA; University of Iowa, Iowa City, IA.

10/11/11

Reference

AK Chaturvedi, EA Engels, RM Pfeiffer, et al. Human Papillomavirus and Rising Oropharyngeal Cancer Incidence in the United States. Journal of Clinical Oncology (abstract). October 3, 2011 (Epub ahead of print).