Trends of colorectal cancer incidence and prevalence in Italian regions.

Incidence and prevalence of tumors of colon and rectum, estimated from mortality and survival data, are presented for Italian regions and for the period 1970-1990. Projected rates to the year 2000 are also given. Age-standardized incidence rates have increased during the considered period. The increase has been higher for southern regions, which had, during the 70's, the lowest incidence and mortality levels. Geographic heterogeneity of colorectal cancer occurrence across Italian regions is therefore decreasing. The phenomenon parallels a tendency towards the homogenization of dietary habits observed in the Italian population. Estimated incidence levels increased less for the younger generation and appear stable for people born after 1940. More than 150,000 prevalent cases were estimated by the year 1990. The number is likely to increase owing to the simultaneous increasing tendency in incidence and survival rates.