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Adenocarcinoma of the Stomach and Other Gastric Tumors

Julian A. Abrams and Michael Quante

Chapter 54 from Sleisenger and Fordtran’s Gastrointestinal and Liver Disease (10th Edition)

Gastric cancer remains a major cause of cancer-related mortality in the world, despite declining rates of incidence in many industrialized countries. In this chapter, we mainly discuss gastric adenocarcinoma, which makes up the majority of gastric malignancies.

Epidemiology

Gastric cancer remains the second leading cause of cancer mortality in the world,1 although the overall incidence is declining.2 In Western countries, the incidence of gastric cancer has decreased dramatically over the past century; in the United States, gastric cancer mortality has decreased 87% since 1950.3 In the USA, the incidence of gastric cancer has diminished to approximately 7.6 cases per 100,000 people,4 whereas as recently as 1945, gastric cancer was the leading cause of cancer mortality in men.5 Gastric cancer is now the 14th leading cause of cancer mortality in the United States.6 It is estimated that in 2012, approximately 21,320 Americans were diagnosed with gastric cancer and that 10,540 died of it.4

There is great geographic variation in gastric cancer incidence, with the highest incidence rates in the Far East (Fig. 54-1). Eastern Europe and Central and South America also have high incidence rates, with the lowest incidence rates observed in North America, North Africa, South Asia, and Australia.7 Although gastric cancer was common in industrialized countries in the past, the latest epidemiologic data indicate that greater than 60% of new cases of gastric cancer are in developing countries, reflecting a more rapid decline in developed countries.

In the USA, the median age of diagnosis is 70 years.4 In Japan, a country with a high incidence of gastric cancer, the mean age of diagnosis is roughly a decade earlier, perhaps reflecting lead-time bias due to widespread screening. The incidence of gastric cancer in males is approximately twice that in females (Table 54-1). The incidence of gastric cancer in blacks in the USA is nearly double that in whites. Native Americans and Hispanics also have a higher risk of development of gastric cancer than whites. In contrast to the pattern seen with non-cardia gastric cancers, the incidence rates of gastric cardia cancer are rising2 ; in the USA, cardia cancers now represent 27% of gastric cancers, up from just 10% in 1975.4

There are numerous dietary, environmental, and genetic risk factors for gastric adenocarcinoma (Box 54-1).