To explore a possible connection between specific environmental factors that might explain the high rates of
stomach cancer in people living in the highlands of western Venezuela, an epidemiologic study was conducted in 2 regions of contrasting topography. The regions embrace 3 Andean states, Mérida, Táchira and Trujillo, and the vicinal lowland surrounding the Maracaibo lake basin of Zulia State. Statistical sanitary records from 1986 to 1996 comprising 5.5 million people in the study area indicated that age-sex-adjusted
gastric cancer death rate per 100,000 people (DR) was up to 3.64 times higher in highland than lowland areas, although total
cancer-related DRs were comparable in both regions. DRs of other less frequent
cancers from the upper alimentary tract [esophagous (1.18/0.99) and mouth-throat (1.39/2.64)] showed comparable values in both regions as well as colorectal, breast, and uterus-cervix
cancers, suggesting that the
stomach cancer DRs were related to geographically determined factors. Comparison of some nutrition issues, incidence of Helicobacter pylori
infection in selected areas, the discovery of the bracken
carcinogen ptaquiloside in milk from bracken-fed cows, the prevalence of this plant in mountain cattle households and pasturelands and the rates of bracken-evoked bovine enzootic
hematuria led us to conclude that consumption of
ptaquiloside-contaminated milk may contribute to human
gastric cancer in the Andean states of Venezuela.