[Descriptive epidemiology of malignant tumors of the colon and rectum].

This paper examines patterns and trends of colon and rectal cancer in different countries and in Italy. Incidence and mortality rates of colorectal cancer vary widely in the world. High rates are characteristic of highly developed countries in North America, northern and western Europe. The lowest rates are found in Asia, Africa and most Latin American countries. The most recent incidence rates for colon cancer from cancer registries around the world published in "Cancer Incidence in Five Continents, 1982" range from 0.6 cases per 100,000 in Dakar, Senegal to 32.3 in Connecticut, USA for males and from 0.7, always in Dakar, to 27.4 among the Japanese population of Bay Area, USA. The Italian cancer registry for Varese, shows a rate of 19.9 for males and 16.9 for females. The incidence rates for cancer of the rectum range from 1.5 per 100,000 in Dakar to 22.6 in the North West Territory and Yukon, Canada. For females the highest rates, 13.9, are in Israel (born in Europe or America) and the lowest always in Dakar, 1.0. The Varese rates are 15.7 and 9.1 for males and females respectively. Regression analysis shows that between incidence rates of colon and rectal cancer, divided by sex, there is a strict correlation. The sex ratios for colon and rectal cancer differ, rectal cancer being distinctly more common among males in most countries, whereas colon cancer affecting both sexes at rather similar rates. Results confirm that there is a higher frequency, for colon cancer in particular, in urban areas than in rural areas. Differences due to race, on the contrary, have found no confirmation. The international incidence trends over the period 1960-1980 show a general increase for colon cancer in both sexes. In Asia the most evident increase have been in Singapore and Miyagi. In Europe, Slovenia (Yugoslavia) and Norway present 40-50% increases. Similar tendencies have been observed for rectal cancer trends. Values more than increase 100%, for both sexes, have been found in Hawaii and Singapore. In Europe, Norway and Slovenia always present the highest increases. Marked geographic variations occur even as regards colon and rectal mortality in the different countries. The highest values for colon cancer have been found in Luxemburg (18.4) for males, and in New Zealand (13.3) for females and the lowest in Honduras for both sexes (0.1 and 0.0 respectively). In Italy the values are 8.0 for males and 6.0 for females.(ABSTRACT TRUNCATED AT 400 WORDS)