Comparative epidemiology of cancer between the United States and Italy.

Available statistics on smoking, alcohol, food supply, reproductive history, and other lifestyle habits from the U.S. and Italy were compared and related to mortality rates of common neoplasms over the period 1955 to 1980. Per capita cigarette consumption has declined in the U.S. since the early 1960s but continues to rise in Italy, chiefly due to the recent increase in cigarette smoking among Italian women. Alcohol consumption has increased in both countries, being persistently about 40% higher in Italy. Changes were relatively limited in the American diet, but substantial for the Italian one which had particularly marked increases in meat, milk, and fat consumption. Fertility rates have declined in both countries but more sharply in the U.S. These lifestyle changes were reflected by distinctly divergent trends in cancer mortality rates between the two countries. In Italian males, mortality rates of urinary bladder cancer and alcohol-related neoplasms of the aerodigestive tract (oral cavity, larynx, and esophagus) increased in a similar manner and were persistently elevated relative to American males. Similarly, Italian lung cancer rates, while starting from lower values, rose steadily to overtake American rates in the younger and middle age groups of both sexes, and neoplasms of the intestines, breast, and ovary, starting from considerably lower values, tended to approach the American rates over the 25-year period considered. Within Italy, mortality rates of most common neoplasms were substantially elevated in the North of the country relative to the South, thereby paralleling the distinct North to South gradient in socioeconomics, diet, and affluent lifestyle which exists in the country. In our opinion, most of these trends are real, and their explanation should be sought, partly or largely, in the changes in tobacco and alcohol use, and the reproductive and dietary patterns described. The evidence presented underlies the importance of this kind of exercise to formulate and test etiological hypotheses of human diseases, which may be overlooked in studies based on populations with more homogeneous lifestyle habits or environmental exposures.