Oropharyngeal Cancer Increasing Rapidly Worldwide

Roxanne Nelson

November 26, 2013

The incidence of oropharyngeal cancer (OPC) has significantly increased during the past 2 decades, and almost exclusively in economically developed nations. This trend underscores the potential role of human papillomavirus (HPV) in this increasing incidence, particularly in men, a new study shows.

The results were published online November 18 in the Journal of Clinical Oncology.

Reports from several countries in recent years have shown a rising incidence of OPCs, note the study authors, led Anil K. Chaturvedi, PhD, from the division of cancer epidemiology and genetics at the National Cancer Institute. Subsequent molecular studies conducted in Australia, Sweden, and the United States reported dramatic increases in the proportion of HPV-positive OPCs since the 1980s. This was most prevalent in men and in people younger than 60 years.

HPV Infection Implicated

Tobacco and alcohol have been the main established risk factors for head and neck cancers, as previously reported by Medscape Medical News.

However, in an earlier case–control study, previous HPV infection increased the risk of developing oropharyngeal cancer by 32, much higher than the 3-fold increase in risk associated with smoking and the 2.5-fold increase associated with drinking (N Engl J Med. 2007;356:1944-1956). Surprisingly, no evidence of a synergy between exposure to HPV and tobacco or alcohol use was seen.

"It's the virus that drives the cancer," senior author of that study, Maura Gillison, MD, PhD, from the Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins in Baltimore, said when it was published. "Since HPV has already disrupted the cell enough to steer its change into cancer, tobacco and alcohol use may have no further impact."

A more recent study found that the incidence of HPV-positive tonsillar tumors almost doubled over each decade from 1970 to 2007, for a cumulative 7-fold increase over that period (Emerg Infect Dis. 2010;16:1671-1677).

In similar fashion, HPV-positive base of tongue cancers increased from 54% in 1998/99 to 84% in 2006/07.

Gender Differences

Dr. Chaturvedi and colleagues used data from the Cancer Incidence in Five Continents database (volumes VI to IX), and identified 182,736 OPCs and oral cavity cancers that occurred from 1983 to 2002 in 23 countries. There were a total of 69,592 OPCs (54,700 in men and 14,892 in women) and 113,144 oral cavity cancers (74,771 in men and 38,373 in women).

They found that for men, OPC incidence increased significantly in Australia, Canada, Japan, Slovakia, and the United States. At the same time, there was a decreasing incidence of oral cavity cancers.

In contrast, for women, in all countries with increasing OPC incidence (Denmark, Estonia, France, the Netherlands, Poland, Slovakia, Switzerland, and the United Kingdom), there was a concomitant increase in incidence of oral cavity cancers

In addition, when they compared the incidence of lung cancer and OPC in men, there were "statistically significant divergent patterns." Except for Brazil, where incidence trends were nonsignificant, the incidence of lung cancer significantly declined in all other countries that had significant increases in OPC. Because smoking is a strong risk factor for lung cancer, OPC, and oral cavity cancer, these data suggest that another factor, such as HPV infection, is a possible explanation for the rising incidence of oropharyngeal cancer, the researchers note.

The opposite was true for women. The incidence trends for OPC and oral cavity cancers were statistically similar in a majority of countries, and lung cancer incidence increased, either significantly (France and the Netherlands) or nonsignificantly (Denmark, Slovakia, and Switzerland). An exception was observed in the United Kingdom, where the incidence of OPC was significantly increased despite significant declines in lung cancer incidence.

These results suggest that tobacco use might partially explain the increasing OPC incidence in women, the researchers write, but there is also the possibility that a "potential effect of HPV among women could have been masked by smoking-related increases in OPC incidence."

Smoking and Alcohol Predominate

Dr. Chaturvedi and his team conclude that the reasons "underlying a male predominance of HPV's potential role on observed incidence trends are currently unclear and need confirmation and further investigation."

However, it could have important implications for male HPV vaccination policies, because prophylactic HPV vaccines could potentially be an effective primary prevention strategy for HPV-associated OPCs in men, they note. But tobacco and alcohol use continue to be the major risk factors for both OPC and oral cavity cancers, and the incidence of oral cavity cancers is 2- to 4-fold higher than that of OPC in most parts of the world. This underscores "the need for prevention strategies targeted toward tobacco and alcohol use."

The study was supported in part by the Intramural Research Program of the US National Cancer Institute and by a grant from the Institut National du Cancer. Coauthor Maura L. Gillison, MD, PhD, from Ohio State University in Columbus, reports a consultant role with GlaxoSmithKline and Bristol-Myers Squibb.

J Clin Oncol. Published online November 18, 2013. Abstract

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