ANNUAL CHANGES IN COLORECTAL-CARCINOMA INCIDENCE IN JAPAN - ANALYSIS OF SURVEY DATA ON INCIDENCE IN AOMORI-PREFECTURE

BACKGROUND. In recent years, the mortality rate for colorectal carcino ma in Japan has rapidly been increasing, and there are indications tha t it may surpass that of gastric carcinoma, with colorectal carcinoma fast becoming one of the main targets of cancer treatment in Japan. ME THODS. Eight thousand three hundred and eighty-six case records of col orectal carcinoma (4479 males and 3907 females; 4691 colon carcinoma c ases and 3695 rectal carcinoma cases), diagnosed over 18 years from 19 74 to 1991 in Aomori Prefecture, were analyzed. RESULTS. Age-adjusted incidence for colorectal carcinoma per 100,000 population were 12.6 an d 8.7 for males and females, respectively, in 1974. The corresponding rates were 20 and 13.6, respectively, in 1980, and 42.5 and 25.6, resp ectively, in 1991. Among patients with colon carcinoma, a higher propo rtion have sigmoid colon carcinoma. The degree of increase in the inci dence of sigmoid colon carcinoma was almost the same as that of right- sided colon carcinoma. By birth cohort analysis, among those born in 1 934 or earlier, the incidence at the same age was higher in the younge r population. CONCLUSION. It is possible that the age-adjusted inciden ce of colorectal carcinoma in Japan will soon resemble that of the whi te population in the United States, in a manner similar to that of Jap anese-Americans. (C) 1996 American Cancer Society.