Trends in oral cancer mortality in Japan: 1950-1993.

Objectives: To investigate trends in mortality rates of oral cancer patients in Japan between 1950 and 1993 by sex, age and cancer site, and compare the results with previous studies to determine whether there are any common characteristics of oral cancer patterns between Japan and European countries.
Material and Methods: The mortality data obtained from the Japanese Vital Statistics were analyzed using the 5-year moving average method, and the mortality rates were adjusted to the 1990 world population by age and sex. Age-specific mortality rates were analyzed by birth cohort.
Results: The age-standardized mortality rates among the males increased from 1.14 per 100,000 person--years in 1952 to 1.84 in 1991, whereas the corresponding rate among females changed little over the same period. Cancer of the tongue was the most common cause of death in Japan among the five studied oral regions: lip, tongue, floor of the mouth, major salivary glands and oropharynx, males aged under 54 born in 1920 or later were found to have an increased risk of such disease.
Conclusion: Further epidemiological investigations are necessary to clarify the etiology of oral cancer in Japan.