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 carcinoma in Japan has rapidly been increasing, and there are indications that it may surpass that of gastric carcinoma, with colorectal carcinoma fast becoming one of the main targets of cancer treatment in Japan.


METHODS
Eight thousand three hundred and eighty-six case records of colorectal carcinoma (4479 males and 3907 females; 4691 colon carcinoma cases and 3695 rectal carcinoma cases), diagnosed over 18 years from 1974 to 1991 in Aomori Prefecture, were analyzed.


RESULTS
Age-adjusted incidence for colorectal carcinoma per 100,000 population were 12.6 and 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, respectively, in 1991. Among patients with colon carcinoma, a higher proportion have sigmoid colon carcinoma. The degree of increase in the incidence of sigmoid colon carcinoma was almost the same as that of right-sided colon carcinoma. By birth cohort analysis, among those born in 1934 or earlier, the incidence at the same age was higher in the younger population.


CONCLUSIONS
It is possible that the age-adjusted incidence of colorectal carcinoma in Japan will soon resemble that of the white population in the United States, in a manner similar to that of Japanese-Americans.
Tamura
K
K
First Department of Internal Medicine, Hirosaki University School of Medicine, Japan.
Ishiguro
S
S
Munakata
A
A
Yoshida
Y
Y
Nakaji
S
S
Sugawara
K
K
D000328:Adult; D000367:Age Factors; D001213:Asian / Q000706:statistics & numerical data; D002277:Carcinoma / Q000453:epidemiology* / Q000401:mortality; D015331:Cohort Studies; D003110:Colonic Neoplasms / Q000453:epidemiology* / Q000401:mortality; D005260:Female; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology / Q000208:ethnology; D008297:Male; D008875:Middle Aged; D012004:Rectal Neoplasms / Q000453:epidemiology* / Q000401:mortality; D012811:Sigmoid Neoplasms / Q000453:epidemiology; D013274:Stomach Neoplasms / Q000401:mortality; D014481:United States / Q000453:epidemiology