[Analysis of mortality by population groups migrating within the country. Tumors of the digestive system].
ABSTRACT This paper analyzes mortality of digestive system cancers in Italy during the years 1981-84 by groups of people migrated inside the country. Individuals born and died in the same region are defined as "stables". "Migrants" indicate individuals for which the region of birth differ from that of residence. Mortality for cancers of oral cavity and pharynx, and of the oesophagus, shows a negative effect of being born in the high risk regions of the north-east and a protective effect of being born in the low mortality regions of the south. Leaving high risk areas brings a positive effect, while to settle there makes mortality getting worse. For stomach cancer, the birth effect is very strong: in this first generation of migrants mortality rates are very similar to those of the stable in the birth areas. A strong migration effect is observed for colorectal cancer mortality: age specific mortality rates in migrants fit well those of host stable population. Liver cancer mortality of migrants from high risk areas approaches the one of the host population. Pancreatic cancer mortality shows a protective effect of being born in the south and a negative effect of residing in the northern high mortality areas.