An epidemiological study of laryngeal cancer in Japan.

This report presents the findings of an epidemiological study of laryngeal cancer in Japan, based on 6,360 cases treated and registered during the 10-year period from 1960 through 1969. The number of the patients increased 1.5 times from 1960 to 1969. Geographically the absolute number of recorded cases was proportional to the population density; in other words, it was larger in heavily urbanized areas and smaller in rural regions. An anatomical classification revealed that the incidence of supraglottic and glottic cancer was about equal (3,121 and 3,176 cases), and subglottic cancer was only 1 percent of the total. Histologically, 98.6 percent were of the squamous cell carcinoma and 1.4 percent were of the basal cell carcinoma, adenocarcinoma, transitional cell carcinoma, etc. As to the age and sex distribution, the majority of the patients were 50 to 70 years old, and those in their 60's were most numerous. The ratio between men and women was 9.6 to 1. 56.1 percent of the patients surveyed were found to have a blood relation with a history of cancer and 31 percent were engaged in occupations where they used their voices frequently. Smoking habits were found in 96 percent of the patients surveyed and as many as 52 percent came under category of heavy smokers. Cigarette smoking might be regarded as a significant factor in laryngeal cancer, while alcohol consumption was not as significant a causal factor as smoking. The living environment had no explicit relationship to laryngeal cancer in the above-mentioned period of years.