Current status of superficial pharyngeal squamous cell carcinoma in Japan

Background: To investigate the status and treatment of superficial pharyngeal squamous cell carcinoma in Japan. Methods: We analyzed all cases diagnosed between 2011 and 2013, as recorded in the national database of hospital-based cancer registries. We extracted data on patient sex, age, tumor locations, histology, presentation routes, initial treatments, and TNM stages. Additionally, we compared the characteristics of pharyngeal carcinoma to those of esophageal cancer. Results: A total of 16,521 oropharyngeal and hypopharyngeal cancers from 409 institutions were included. Diagnosis of Tis tumors was infrequent, and both cancers were likely to be diagnosed at an advanced stage (n = 866, 5.3%). Tis diseases were the most commonly detected during follow-up examinations for other diseases (n = 608, 70%). While more oropharyngeal Tis patients were men compared to T1–4 patients (88 vs 82%, respectively), hypopharyngeal cancer patients comprised an equally high proportion of men (94 vs 92%, respectively). The most common location of oropharyngeal Tis tumors was the posterior wall (32%), whereas T1–4 tumors were most commonly found on the lateral wall (36%). In hypopharyngeal cancer, both Tis and T1–4 were most commonly located in the pyriform sinus (62%). The proportion of Tis tumors diagnosed at individual institutions showed a positive correlation with the number of endoscopic treatments (r = 0.32, P < 0.001) and the number of esophageal cancer cases (r = 0.37, P < 0.001). Conclusion: Our national database study elucidated the current characteristics of superficial pharyngeal squamous cell carcinoma patients in Japan. Further improvements in early diagnosis and standardized treatments are warranted.