Epidemiology of Skin Cancer in Japan

Abstract

In this article, the changes in the mortality rates of malignant melanoma (C43 in the ICD-10 codes) and other skin cancers (C44) in Japan from 1999 to 2014 are discussed from the viewpoint of descriptive epidemiology, employing the vital statistics data. The crude mortality rates of C43 and C44 increased parallel to age, and that of C44 rapidly increased after 80 years of age. The crude mortality rates of C43 and C44 have been increasing for both males and females. The crude mortality rates in 2014 were from 1.6- to 2.0-fold those in 1999. The male/female ratios of both C43 and C44 were almost 1.0. The correlation coefficient between the age-adjusted mortality rate of C44 and the year was 0.523 (p < 0.05), which suggests that its mortality is increasing, independent of the aging of the Japanese population. The correlation coefficient between the age-adjusted mortality rate of C43.5-7 (malignant melanoma; trunk, upper limb, lower limb) was 0.925 (p < 0.05), and that of C44.0-4 (other skin cancers, head and neck) was 0.637 (p < 0.05). The correlation coefficient between the crude mortality rate of C44.0-4 (other skin cancers, head and neck) and the latitude of the capital of each of the 47 prefectures of Japan was negative, but that of C43 was positive. In Japan the amount of ultraviolet (UV) B exposure has been increasing almost continuously, but the present results suggest that the contribution of UV to the occurrence of malignant melanoma is not large. The westernization of the lifestyle of Japanese people may have something to do with the continuous increase in C43.5-7. It is not contradictory that the increasing amounts of exposure to UV radiation have brought about an increase in squamous cell carcinoma, one of whose causes is UV radiation, and consequently an increase in the age-adjusted mortality for C44.