Guest Post by Scott M. Lippman, MD
UC San Diego Moores Cancer Center
The incidence of cancers of the oropharynx, including the tonsils and base of tongue, has increased dramatically over the past two to three decades in many developed countries worldwide and is rapidly becoming an epidemic health problem in the United States. Anil Chaturvedi, PhD, a world-renowned investigator in this field at the NCI Division of Cancer Epidemiology & Genetics, Infections and Immunoepidemiology Branch, and his colleagues made this projection about the future burden of oropharyngeal cancers (estimated by projecting observed incidence rates from nine SEER registries): by 2010, oropharyngeal incidence among men will have surpassed the incidence of cervical cancer (in women); by 2020, over 70 percent of oropharyngeal cancers will be HPV-positive; and by 2030 oropharyngeal cancers will likely constitute a majority of all head and neck cancers in the United States.
Epidemiologic studies show that these increases are caused by rising incidence of HPV-positive oropharyngeal cancers (OPC), believed to be a consequence of rising exposure to oral HPV infection in recent birth cohorts from changes in sexual behaviors. A possible alternative hypothesis is that the substantial declines in recent decades in the conduct of childhood tonsillectomy could have led to rising incidence of tonsil cancers.
Curiously, in the 1950s (decades before HPV-related tonsil cancer was diagnosed and became endemic), prophylactic bilateral tonsillectomy (and occasionally prophylactic radiation) was standard of care to prevent tonsillitis in children in the United States, Denmark, and other developed countries. While long abandoned, these erstwhile treatment guidelines based on societal norms at that time have fortuitously provided an opportunity to explore the current major medical and public health problem of HPV-related OPC.
Published today in the AACR journal Cancer Prevention Research, a population-based study by Fakhry and colleagues provides the first insight into the association of childhood tonsillectomy with future risk of OPC. They conducted an analysis within the Danish Cancer Registry and showed that prophylactic tonsillectomies as a child were associated with a dramatically (>80 percent) reduced subsequent risk of tonsil cancer, but were unrelated to risk of base of tongue cancers.
In an accompanying editorial, Chaturvedi notes that this report is clearly a “first.” While these results are provocative, they should be considered preliminary and should not influence clinical practice at this time. The findings provide a foundation for future clinical and scientific/mechanistic studies, e.g., for replication in different settings and populations. He discusses the implications of this new observation as a clinical signal for prevailing questions in the field related to risk predictors (e.g., genomics), role of immune system in HPV-related cancer development (tonsils are rich sites of immune tissue), rising incidence, role, and uptake of the HPV vaccine, early detection (e.g., the “Pap smear” which works so well for cervical cancer does not work for tonsil cancer, even though both cancers are caused by the same virus), secondary prevention, and treatment of OPC.
This primary, provocative report will likely stimulate further, larger, and more detailed registry and epidemiologic studies to confirm and extend this new finding and lead to biologic/mechanistic studies of risk and prognosis in this setting. Hopefully, this report will also put renewed attention and focus on early detection research and secondary prevention of the rapidly growing public health problem of HPV-related disease.
Scott M. Lippman, MD, is director of the UC San Diego Moores Cancer Center, editor-in-chief of the AACR journal Cancer Prevention Research, and member of the AACR board of directors. Read his full bio.
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