We love to hear from our readers—the dentists of Canada. Please send us your letters, comments or feedback on any articles that you’ve read in the magazine. Email: publications@cda-adc.ca The views expressed are those of the author(s) and do not necessarily represent the opinions and official policies of CDA. The editorial department reserves the right to edit all copy submitted to CDA Essentials. Thank you for your letter and interest in the CDA Essentials article1 on oropharyngeal cancer (OPC), I would like to emphasize that the potential of HPV vaccination to mitigate the development of HPV-related OPC still remains fully unexplored. Well-designed studies are absent due to the relatively recent implementation of HPV vaccination and the late development of HPV-associated OPC.2,3 Nevertheless, both the United States and Canada offer the 9-valent HPV vaccine, which was granted accelerated approval by the Food and Drug Administration, recognizing its efficacy in preventing oropharyngeal and other head and neck cancers caused by HPV strains. It’s crucial to note that althoughHPV-positiveOPC and anogenital cancer share similar carcinogenic mechanisms, they differ in epidemiological factors, HPV types, mutational profiles, cell-of-origin, treatment response, and clinical behaviour, which suggests molecular-level distinctions. In contrast to cervical cancer, HPV-associated OPC does not have an identifiable precursor stage that can be screened for and managed, which further complicates diagnosis and adds to the urgency of preventing OPC before it initiates and progresses.4 GARDASIL-9, the soleHPVvaccine available in theU.S. since2016, provides protectionagainst high-riskHPVvariants associated with OPC, underscoring its potential in disease prevention. Evidence regarding the impact of the HPV vaccine on oropharyngeal disease primarily stems from studies demonstrating a reduction in oropharyngeal HPV infection post-vaccination.5–7 For instance, in a trial6 initially designed to evaluate the efficacy of the bivalent HPV vaccine against cervical HPV disease among 7466 females in Costa Rica, a lower proportion of participants who received the bivalent HPV vaccination (1 out of 2910) showed detectable HPV types 16 or 18 in oropharyngeal specimens 4 years post-vaccination compared to those receiving the control hepatitis A vaccination (15 out of 2924). Moreover, retrospective studies indicating a decreased prevalence of oropharyngeal vaccine-type HPV among unvaccinated individuals following vaccine introduction suggests the potential for herd immunity against oropharyngeal HPV infection.8 Many of the studies on vaccines and HPV oral infections have used oral HPV 16 as a marker or HPV antibody positivity in the oral samples, such as saliva, to examine the relationship between HPV vaccination and OPC incidence.2,3 Long-term follow-up will assist in determining the effectiveness of HPV antibodies or oral HPV as an indicator of immunity against HPV-associated OPC. Continued research and public health efforts are imperative to maximize the impact of HPV vaccination on preventing OPC.2,9 Firoozeh Samim, DMD, MSc, FRCD(C), Dip ABOMP Assistant Professor, McGill University, Faculty of Dental Medicine and Oral Health Sciences Author Response References: 1. Increase in oropharyngeal cancers. CDA Essentials. 2024;11(1):22-23. [accessed 2024 Apr 18]. Available: cda-adc.ca/en/services/ essentials/2024/issue1/22 2. Macilwraith P, Malsem E, Dushyanthen S. The effectiveness of HPV vaccination on the incidence of oropharyngeal cancers in men: a review. Infect Agent Cancer. 2023 Apr 24;18(1):24. 3. Katz J. The impact of HPV vaccination on the prevalence of oropharyngeal cancer (OPC) in a hospital-based population: A crosssectional study of patient’s registry. J Oral Pathol Med. 2021 Jan;50(1):47-51. 4. Berman TA, Schiller JT. Human papillomavirus in cervical cancer and oropharyngeal cancer: One cause, two diseases. Cancer. 2017 Jun 15;123(12):2219-2229. 5. Wilkin TJ, Chen H, Cespedes MS, Leon-Cruz JT, Godfrey C, Chiao EY, et al. A randomized, placebo-controlled trial of the quadrivalent human papillomavirus vaccine in human immunodeficiency virus-infected adults aged 27 years or older: AIDS clinical trials group protocol A5298. Clin Infect Dis. 2018 Oct 15;67(9):1339-46. 6. Herrero R, Quint W, Hildesheim A, Gonzalez P, Struijk L, Katki HA, et al. Reduced prevalence of oral human papillomavirus (HPV) 4 years after bivalent HPV vaccination in a randomized clinical trial in Costa Rica. PLoS One. 2013 Jul 17;8(7):e68329. 7. Schlecht NF, Masika M, Diaz A, Nucci-Sack A, Salandy A, Pickering S, et al. Risk of oral human papillomavirus infection among sexually active female adolescents receiving the quadrivalent vaccine. JAMA Netw Open. 2019; 2(10): e1914031. 8. Mehanna H, Bryant TS, Babrah J, Louie K, Bryant JL, Spruce RJ, et al. Human papillomavirus (HPV) vaccine effectiveness and potential herd immunity for reducing oncogenic oropharyngeal HPV-16 prevalence in the United Kingdom: A cross-sectional study. Clin Infect Dis. 2019 Sep 27;69(8):1296-1302. 9. Chaturvedi AK, Graubard BI, Broutian T, Xiao W, Pickard RKL, Kahle L, et al. Prevalence of oral HPV infection in unvaccinated men and women in the United States, 2009-2016. JAMA. 2019 Sep 10;322(10):977-979 Letters 41 Issue 3 | 2024 |
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