[Purpose] The validity of the risk classification according to Ang for human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC) remains to be studied in patients treated by methods other than chemoradiotherapy and in Japanese patients. In this study, the validity of Ang's risk classification was studied in Japanese patients treated using various methods, including surgery.
[Material and Method] Between 2010 and 2018, 122 patients with HPV-related OPSCC stages III and IV according to the TNM classification 7th edition (TNM-7) were treated curatively at a single institution in Japan. The median age was 62.7 years. Sixty-seven patients (54.9%) were classified as stage I according to the TNM 8th edition (TNM-8). Over 50% of the patients underwent surgery with or without adjuvant therapy. The influence of multiple factors on survival was determined.
[Results] Age, amount of smoking, secondary cancer, and N-stage according to the TNM-7 significantly influenced survival. Ang's risk classification was also predictive of prognosis, but if 30 pack-years (PYs) instead of 10 PYs is employed to dichotomize the amount of smoking, the new risk classification can significantly better predict prognosis. According to the new risk classification, favorable and unfavorable risk patients showed 5-year progression-free survival, disease-specific survival, and overall survival rates of 72.7% and 35.9%, 94.6% and 76.2%, and 92.6% and 62.7%, respectively.
[Conclusions] Even in patients treated by methods other than chemoradiotherapy and in Japanese patients, the combination of the amount of smoking and neck node status is useful in prognosis prediction.