Epidemiology of gastric cancer

Abstract

fallen dramatically over the past 70 years [1] .Despite its recent decline, gastric cancer is the fourth most common cancer and the second leading cause of cancer-related death worldwide [2,3] .In 2000, about 880 000 people were diagnosed with gastric cancer and approximately 650 000 died of the disease [4] .The two main tumor sites of gastric adenocarcinoma are proximal (cardia) and distal (noncardia).Despite a decline in distal gastric cancers, proximal tumors have been increasing in incidence since the 1970s, especially among males in the Western countries [5,6] .These gastric tumor types predominate in populations from different geographic locations, racial and socio-economic groups.They may also differ in genetic susceptibility, pathologic profile, clinical presentation, and prognosis.The observed differences between gastric cancers by anatomic site suggest that they are distinct diseases with different etiologies.Detailed epidemiological analyses of their demographic trends and risk factors will help guide future cancer control strategies. PATHOLOGIC CONSIDERATIONSAbout 90% of stomach tumors are adenocarcinomas, which are subdivided into two main histologic types:( 1 ) we l l -d i f f e r e n t i a t e d o r i n t e s t i n a l t y p e, a n d ( 2 ) undifferentiated or diffuse type.The intestinal type is related to corpus-dominant gastritis with gastric atrophy and intestinal metaplasia, whereas the diffuse type usually originates in pangastritis without atrophy.The intestinal type is more common in males, blacks, and older age groups, whereas the diffuse type has a more equal male-to-female ratio and is more frequent in younger individuals [7,8] .Intestinal type tumors predominate in highrisk geographic areas, such as East Asia, Eastern Europe, Central and South America, and account for much of the international variation of gastric cancer [9] .Diffuse type adenocarcinomas of the stomach have a more uniform geographic distribution [10] .A decline in the incidence of the intestinal type tumors in the corpus of the stomach accounts for most of the recent decrease in gastric cancer rates worldwide [11] .In contrast, the incidence of diffuse type gastric carcinoma, particularly the signet ring type, has been increasing [12] . DEMOGRAPHIC TRENDS Time trendsIn the 1930s, gastric cancer was the most common cause of cancer death in US and Europe.During the past 70 years, mortality rates have fallen dramatically