Abstract
Oral cancer is a rare cancer that accounts for 1％ of all cancers, or about 6 per 100,000 people. In 2014, the Japanese Ministry of Health, Labour, and Welfare （MHLW） created the “10-Year Strategy for Cancer Research” and designated “oral cancer” as a priority research area as a rare cancer that is difficult to study. Since there are limitations in conducting high-quality clinical research at individual institutions, multi-institutional research is becoming increasingly important. The Japanese Society of Oral Oncology has established a joint research committee, and various studies are being conducted. This study is a prospective, multi-institutional, non-randomized observational study. The choice of whether to perform elective neck dissection （END） for clinically node-negative （cN0） oral tongue squamous cell carcinoma （OTSCC） at the same time as resection of the primary tumor is based on institutional policy and patient preference. The primary endpoint of this study is 3-year overall survival. The secondary endpoints are 3-year disease-specific survival, 3-year relapse-free survival, and the impact on patient quality of life （QoL）. The impact of QoL is assessed by using the Functional Assessment of Cancer Therapy-Head and Neck （Version 4; FACT-H&N） and the Disabilities of the Arm, Shoulder, and Hand （DASH） questionnaire. Confounding factors will be adjusted to reduce selection bias. The results of this study may provide new outcome-oriented insights into the efficacy of END for cN0 OTSCC in terms of patient QoL in Japan.
