Cancer epidemiology in populations of the United States--with emphasis on Hawaii and California--and Japan.

The population of California and the San Francisco Bay Area has a number of ethnic components that differ in the frequency with which certain cancers occur. Mortality rates of California Janpanese and incidence data from the cancer reporting system of the Bay Area are analyzed for the cancer sites considered related to nutrition. The American Japanese of California are particularly amenable to epidemiological study because of the cancer data available from Japan for comparison with that of the California Japanese. The cancer rates occurring among the successive generations of the Japanese in California are compared to the rates in Japan and the white rates for the Bay Area. Gastric cancer rates undergo a stepwise reduction from the high rates in Japan to the intermediate rates of immigrant Japanese and the lower rates for the American born. Colon cancer rates are increased about equally in both generations of Japanese and are approaching the white rates. Cancers of the breast, uterine corpus, and ovary in women and the prostate for men are rapidly approaching the rates for the white population. Etiologies are continually being identified or indicated for a number of these cancers by epidemiological studies, and more specific identification of carcinogenic mechanisms should be possible by other disciplines.