Increasing prevalence of HPV in oropharyngeal carcinoma suggests adaptation of p16 screening in Southeast Asia.

Background: Human papillomavirus (HPV) is etiologically linked to increasing oropharyngeal squamous cell carcinoma (OPSCC) rates in the Western world. However, the role of HPV in Southeast Asia, a high incidence region, hasn't been assessed.

Methods: 96 formalin-fixed, paraffin-embedded (FFPE) tissue blocks and corresponding patient data were obtained from Srinagarind Hospital, Thailand from 2012-2017. DNA from areas of 70 %+ cellularity were genotyped using polymerase chain reaction (PCR) and stained for p16, a surrogate marker for HPV. Inverse probability weights based on data from the hospital-based cancer registry were used in statistical analyses. Adjusted linear regression was used to assess changes in OPSCC HPV prevalence and conduct projections. Kaplan-Meier and Cox proportional hazard models were used to determine HPV-specific survival differences.

Results: 14 patients exhibited monoinfection with HPV16, two with HPV18 and one was HPV16/18 coinfected. PCR results were in agreement with p16 staining. On average, HPV + patients were more likely to have tonsil cancer (p-value:0.002). HPV prevalence increased by 2% annually (pvalue: 0.01), from 16 % in 2012 to 26 % in 2017. At the current rate, OPSCC HPV positivity will exceed 50 % by 2030. HPV positivity was shown to be protective in Kaplan-Meier (log-rank p = 0.02) and sex, age and stage adjusted Cox models (HR:0.34 [95 %CI:0.22, 0.52]).

Conclusion: Given the increased prevalence and similarities in presentation of HPV + OPSCC to those observed in Western countries, the data suggest the adaptation of p16 staining and subsequent restaging of OPSCC tumors as suggested by the American Joint Committee on Cancer in Southeast Asia.