[Mortality from malignant tumors of the digestive system in an area of the province of Milan from 1980 to 1987].

In a highly populated and industrialised zone of the province of Milan (Health Area 68, Rho) a study was made of mortality due to malignant neoplasms of the digestive organs in the years 1980-1987. The highest mortality percentage in both sexes is caused by stomach cancer, followed by neoplasms of the large bowel, particularly of the colon, malignant neoplasms of the pancreas, primary liver cancer and, in males, of the oesophagus. On the whole mortality from malignant neoplasms of the digestive organs is high in subjects over 75 years and in males a little earlier. Age standardised mortality rates of malignant neoplasms of the stomach and intestine are higher in the area being studied than in Italy. However in males mortality from cancer of the large bowel is lower than in Lombardy, especially in middle-aged subjects. The years 1980-87 have shown a statistically significant increasing trend in males of death from cancer of the colon, rectum and liver. There is an identical trend in females as regards cancer of the colon and liver with the addition of stomach cancer but mortality from cancer of the rectum is stationary. In both sexes mortality from malignant neoplasms of the digestive organs is on the increase but in females this coincides with a general increase in cancer mortality as a whole. Differences have emerged, however, between the sexes depending on age: in males the increasing trend refers mainly to the 35-64 year age group and in females to the over 65 age group. This is particularly true in the case of tumours of the large bowel. In the area being examined the middle-aged population was particularly affected by immigration caused by the rapid industrial development of the area in the 1960's and 70's. It is reasonable to assume that the increasing trend in tumours of the digestive organs, and in particular of the large bowel can also be explained by the fact that people coming on the whole from regions with a lower specific risk factor have had to adapt to different life styles and dietary habits that are typical of a highly industrialised metropolitan area. This assumption can be verified with case-control studies or with statistical techniques (e.g. the logistic regression model for the analysis of proportionate mortality data) that are more typical of occupational epidemiology. In this way it would be possible to understand better the effects of living in the area being studied, as well as of more specific risk factors.