Abstract
BACKGROUND: In Western countries, the incidence of gliomas increases with advancing age. However, no accurate population-based epidemiological survey of gliomas in Japan has been reported. METHODS: We examined the incidence of glioma in a well- defined population residing in Kumamoto prefecture (population 1.86 million in 2001) in southern Japan. RESULTS: During the period from 1989 to 2013, 1,382 patients harboring gliomas were diagnosed; 1,027(74.3 %) tumors were confirmed microscopically. The age-adjusted incidence rate was 2.9 (males, 3.3; females, 2.5) per 100,000 population per year. During the 25 years from 1989 and 2013 there was an increase in the incidence of glioma; the number of gliomas diagnosed in the last 5 years was almost twice that of the first 5 years. Its incidence increased with age; the highest rate was observed in males and females older than 80-years and the age-specific incidence per 100,000 per year was 9.1 for males and 6.0 for females. Although the number of elderly individuals doubled during this study period, the number of malignant gliomas in this group showed a five-fold increase. CONCLUSION: Although the incidence of glioma remains lower in Japan than in Western countries, it is on the increase. Besides the aging of the population, environmental changes may account for the increase in the incidence of malignant gliomas in Japan.