Global epidemiological studies have shown that oral cancer is one of the five commonest cancers in males, excluding skin cancer, on the basis of incidence, mortality, and relative frequency data. However, the prevalence of oral cancer varies among different parts of the world and also among different sublocations of the oral cavity. In Japan, deaths from oral cancer account for only 1% to 2% of all cancer deaths. However, the number of deaths and the mortality rate due to oral cancer have increased in recent years.
In the present paper, we report on the epidemiology of oral cancer in Japan. Date used for analysis were mainly derived from the Japanese population statistics from 1950 through 1993, published by the Ministry of Health and Welfare.
The number of annual deaths from “all oral cancers” (lip, oral, oropharyngeal, and salivary gland cancer) showed a 4.5-fold increase (5.2-fold in men and 3.4-fold in women) from 698 to 31554 during the 44 years between 1950 and 1993. The male-to-female ratio also increased from 1.6: 1 to 2.5: 1. The number of deaths increased for all oral cancers excluding lip cancer. Tongue cancer was the most common and contributed to about 40% to 60% of all oral cancer deaths. The crude death rates for men showed an approximately 3.5-fold increase and age-adjusted death rates an approximately 1.5-fold increase during the period between 1950 and 1991. For women, the crude death rates increased steadily (an approximately 2-fold increase in total), while the age-adjusted death rates remained unchanged. In men, the ageadjusted death rates tended to increase for cancers of the oropharynx, salivary gland, floor of the mouth, and gingiva, while it tended to decrease for cancers of the tongue and lip. In women, the same trends were noted as in men, although the changes were smaller. The overall age-specific mortality rates remained virtually unchanged for the age group of 40 to 49 years, but increased in all age groups over 50 years, especially that 65 years or older.
We also attempted to predict morbility and mortality patterns of oral cancers in Japan. The incidence of oral cancers is expected to increase in both sexes, especially in men. Both crude and age-adjusted death rates will increase substantially more in men than in women.
