The striking geographical pattern of gastric cancer mortality in Spain: environmental hypotheses revisited

Smoothed relative risks of stomach cancer mortality were obtained, using the Besag-York-Molliè autoregressive spatial model. Maps depicting relative risk (RR) estimates and posterior probabilities of RR being greater than 1 were plotted.From 1994-2003, 62184 gastric cancer deaths were registered in Spain (7 percent of all deaths due to malignant tumors). The geographic pattern was similar for both sexes. RRs displayed a south-north and coast-inland gradient, with lower risks being observed in Andalusia, the Mediterranean coastline, the Balearic and Canary Islands and the Cantabrian seaboard. The highest risk was concentrated along the west coast of Galicia, broad areas of the Castile & Leon Autonomous community, the province of Cáceres in Extremadura, Lleida and other areas of Catalonia.In Spain, risk of gastric cancer mortality displays a striking geographic distribution. With some differences, this persistent and unique pattern is similar across the sexes, suggesting the implication of environmental exposures from sources, such as diet or ground water, which could affect both sexes and delimited geographic areas. Also, the higher sex-ratios found in some areas with high risk of smoking-related cancer mortality in males support the role of tobacco in gastric cancer etiology.Gastric cancer has plotted a trend very different to that of other malignant tumors in recent decades, with a marked decline in incidence and mortality, described by the scientific community as an "unplanned triumph" [1]. However, this tumor still ranks fourth in terms of incidence and second in cancer mortality worldwide [2]; in 2002, there were more than 900,000 new cases of gastric cancer around the world, 66% of which occurred in less developed countries [3].One of this tumor's epidemiologic characteristics is the presence of marked geographic differences worldwide. The highest incidence rates have been reported in Korean and Japanese cancer registries, where rates are tenfold those of the U