An hypothesis on the presumed association between thyroid goiter and gastric cancer

Excerpt

Epidemiologists have long suspected on the basis of ecological studies a relationship between the incidence of gastric cancer and iodine-deficient goiter. This relation was initially put forward by Percy Stocks in 1925 who noted that countries in Europe that had the highest prevalence of goiter also had the highest cancer mortality [1]. In the United States, a correlation was also noted between the prevalence of goiter and mortality from gastric cancer. Seventy years ago, the highest incidence of gastric cancer in the United States was found in the upper Midwest, especially in Wisconsin, the Dakotas, Minnesota, and around the Great Lakes [2]. In this part of the country, the soil has a low concentration of iodine. As expected, the incidence of iodine-deficient goiter was highest in the same region, especially near the Great Lakes. Historically, before the supplementation of table salt with iodine, this region was described as the “goiter belt.” In the Chicago area, between 1936 and 1948, the estimated prevalence of goiter was nearly three times the prevalence reported on the Atlantic Coast based on the number of hospital admissions [3]. However, despite these associations, it was not possible to ascribe causation because of the bias and population heterogeneity inherent in ecological studies [4]. …