Gastric Cancer in Colombia. III. Natural History of Precursor Lesions 2

Abstract

The premalignant process in the gastric mucosa was studied by gastroscopic surveys of Colombian populations, and the prevalence of superficial gastritis, chronic atrophic gastritis, and intestinal metaplasia was calculated for population samples having a very high gastric cancer risk (Nariño), very low risk (Cartagena), and intermediate risk (Cali). The prevalence of individuals with normal mucosa in successive age groups was used to estimate "depletion" curves, which were taken as indicators of the dynamics of the premalignant process in each community. Differences corresponding to the geographic variation in stomach cancer risk were found: In the high-risk areas of Nariño, around 75% of the population developed some type of gastritis by 45 years of age, whereas in the low- and intermediate-risk population of Cartagena and Cali, the proportion of such lesions did not exceed 50% at age 45 or thereafter. The effect of environmental factors in early life seemed to be important in determining the prevalence of lesions in each population.

Delayed rise in incidence of gastric cancer in females results in unique sex ratio (M/F) pattern: etiologic hypothesis

“…In Nariño [25], a high-risk area for GCA in Colombian, 23.5% of men in the age group 25 to 44 years had H. pylori nonatrophic gastritis compared with 13.6% of females. Klein and co-workers [26] described the natural history of the infection in Peruvian children aged 6 to 30 months.…”

Development of an Empirically Calibrated Model of Gastric Cancer in Two High-Risk Countries

“…A number of assumptions were necessary for the model and we informed these in three ways. First, we established initial ranges for most model parameters by conducting a literature review on the precancerous process of gastric cancer for each country and selecting the highest and lowest values among all available studies (7)(8)(9)(10)(11)(14)(15)(16)(17). Second, we conducted a series of sensitivity analyses to identify influential parameters, followed by calibration exercises in which we manipulated one uncertain variable at a time and visually examined the influence of that parameter on model output approximation to empirical data.…”

Plasma Selenium Measurements in Subjects from Areas with Contrasting Gastric Cancer Risks in Colombia

“…Its inhabitants are of mixed Spanish and Amerindian ancestry and have an agriculture-based economy. In the low-risk area of Tumaco on the Pacific coast (estimated incidence rate of 6/100,000 in similar coastal areas in 1976) (27), the population is of Spanish-African ancestry and the economy is based on fishing. These areas are about 143 miles apart.…”