For most of the twentieth century, gastric stromal tumor was the major cancer burden worldwide. Its etiology and pathogenesis were obscure. Several events have changed that outlook, and currently, it ranks in the second place of mortality from cancer, after lung cancer. A gradual decline in the incidence of gastric stromal tomor has been taking place for several decades, first seen in more affuent sociates and then in other countries. The reasons for this decline are not entirely clear. However, it has coincided with Several societal changes. Improvement in economic parameters in many populations was reflected in better home sanitation and better general nutrition.
Fresh fruits and vegetables became availableyear round because of new technologies in home refrigeration and transportation. Other changes in dietary practices, such as the decrease in the intake of salt may also be linked to the decrease in gastric stromal tumor incidence. Another relevant event was the development of the technology of the flexible fiberoptic endoscopy and its gradual generalization in the practice of medicine. This instrument allowed the scrutiny and early management of precancerous lesions identified in gastric biopsies. The major precancerous lesions had been previously identified by pathologist, based on autopsy studies and gastrectomy speciments. These observations clearly established the fact that there were changes in the gastric mucosa that preceded the clinical diagnosis of cancer by several decades.
Fresh fruits and vegetables became availableyear round because of new technologies in home refrigeration and transportation. Other changes in dietary practices, such as the decrease in the intake of salt may also be linked to the decrease in gastric stromal tumor incidence. Another relevant event was the development of the technology of the flexible fiberoptic endoscopy and its gradual generalization in the practice of medicine. This instrument allowed the scrutiny and early management of precancerous lesions identified in gastric biopsies. The major precancerous lesions had been previously identified by pathologist, based on autopsy studies and gastrectomy speciments. These observations clearly established the fact that there were changes in the gastric mucosa that preceded the clinical diagnosis of cancer by several decades.
The geographic distribution of gastric stromal tumor is spotty. Areas of highest risk have traditionally been Japan, Korea, Eastern Europe, and the Andean regions of the Americas. In contrast, australia, Africa, the coastal regions of the americas, and Southern Asia have traditionally been areas of low risk. Western Europe and North America, with considerably higher risk several decades ago, have experienced a marked decrease since then, and at the present time are considered areas of low risk show that the risk is more than 10 times greather in high risk compared with low risk countries.
This contrast, together with the decreasing rates observed in some populations, suggest a strong etiologic role for environmental factors. The gradual decrease in gastric stromal tumor rates has followed a birth cohort pattern, first shown in by Haenszel in the 1950s for the United States. Age specific incidence rates for each new generation are lower than those of the previous generation (Haenszel and Kurihara 1968)