Oral Squamous Cell Carcinoma Incidence in Japan Based on National Cancer Registry Data 2016-2019.

Introduction: No comprehensive national profiles of oral squamous cell carcinoma (OSCC) have been established in Japan. We set out to describe the profiles of OSCC cases, including demographic characteristics, regional disparities, and survival time on a national basis, using a population-based dataset in Japan. Methods: Using the national cancer registry (NCR) of Japan, we aggregated data on cases of OSCC from 2016 to 2019 that were classified according to the diagnostic criteria specified in the Japanese oral cancer guidelines. We calculated annual, detailed site-specific distributions by sex and age-standardized incidence rates for each year. The standardized incidence ratios by prefecture were computed using 2016 to 2019 data. One-year overall survival was estimated using the Kaplan-Meier method. Univariate and multivariate analyses were conducted using the Cox proportional hazards model. Results: Between 2016 and 2019, data were obtained on 30,537 OSCC incidence cases. In the most recent year, 2019, 57.0% of patients were men, and the mean age was 70.3 years. Among the specific OSCC sites, the tongue was the most common, accounting for more than half the cases. Over half the cancers were localized at the time of diagnosis. The age-standardized incidence rate in 2019 was 5.12 per 100,000 population. The standardized incidence ratios of OSCC among different prefectures ranged from 0.77 (Gifu Prefecture) to 1.37 (Miyagi Prefecture). The one-year survival rate for all OSCC cases diagnosed between 2016 and 2019 was 83.5%. Cox proportional hazards model analysis, adjusted for all covariates, revealed that women had a significantly lower risk of death within one year than men (hazard ratio = 0.81, 95% confidence interval = 0.76-0.87). Conclusions: Our study provides an overview of OSCC epidemiology in Japan using the NCR population-based dataset.