Non-Robustness of Ang's Risk Classification in Human Papillomavirus-Related Oropharyngeal Squamous Cell Carcinoma in Japanese Patients

Simple Summary Human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC) has a favorable prognosis in comparison to HPV-unrelated OPSCC. Risk classification by Ang is known to predict prognosis of HPV-related OPSCC, but it remains to be studied whether it is useful in predicting prognosis in operatively treated Japanese patients. HPV-related OPSCC treated from 2010 to 2018 in a single Japanese institution by various methods were analyzed. We found that Ang's risk classification lost its statistical significance in predicting prognosis in the multivariate analysis and it turned out to not be a robust prognostic factor for Japanese patients with HPV-related OPSCC treated by various methods. Additionally, Ang's risk classification was not prognostically significant in the patients treated by definitive radiation in this series. Smoking appeared to have a larger impact on prognosis in the operatively treated patients than in the radiotherapeutically treated patients. Background: Validity of the risk classification by Ang for human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC) remains to be studied in the patients treated by modalities other than chemoradiotherapy and in Japanese patients. Materials and Methods: Between 2010 and 2018, 122 patients with HPV-related OPSCC in stages III and IV by the TNM classification 7th edition (TNM-7) were treated curatively at a single institution in Japan. The median age was 62.7 years. Over 50% of the patients underwent surgery with or without adjuvant therapy. The influence of multiple factors on survival was analyzed. Results: The amount of smoking dichotomized at 10 pack-year, which was used in Ang's risk classification, was not predictive of prognosis, and Ang's risk classification was not significantly influential on prognosis in multivariate analysis. In the patients treated with definitive radiation therapy, Ang's risk classification was not predictive of the prognosis in univariate analysis. The impact of smoking was significant only in the patients undergoing the definitive operation. Conclusions: Ang's risk classification was not robust in predicting the prognosis of general Japanese HPV-related OPSCC patients. The amount of smoking might have different prognostic influences depending on the therapeutic method.