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Since 2002, we have been conducting a collaborative epidemiologic appraisal of host and environmental factors for stomach and colorectal cancer in several South‐east Asian countries. Ecological and case‐control studies are now being carried out in Hanoi and Ho Chi Minh City, Vietnam; Khon Kaen, Thailand; and Yogyakarta and Semarang, Indonesia, in order to take advantage of the major variation in cancer incidence among these geographical areas and also with data for Japan. Stomach cancer incidence rates in Hanoi, Ho Chi Minh City, Khon Kaen, Yogyakarta and Semarang are approximately 1/2, 1/4, 1/10, 1/50 and 1/100 those prevailing in Japan, respectively: the annual age‐adjusted incidence rates for Semarang were 0.6/105 for men and 0.3/105 for women during 1990–1999, and the respective figures for Japan in 1995 were 67/105 and 27/105.(1,2)
Gastric cancer may be caused by environmental or lifestyle risks, host genetic polymorphisms, as well as aging.(3) Many laboratory studies have pointed to roles for carcinogenic substances, including amine pyrolysate products and nitrosamines; however, grilled or barbecued meat and fish are categorized as possible risk factors in humans.(3) A probable risk factor for stomach cancer is salt or salty foods, which act synergistically with Helicobacter pylori (H. Pylori) infection in the development of stomach cancer in experimental animals(4) and humans.(5) Convincing preventive factors are vegetables and fruit and refrigeration, and a probable preventive factor is vitamin C. The International Agency for Research on Cancer (IARC) has concluded that gastric cancer is a smoke‐related malignancy.(6)H. pylori is a definite carcinogen,(7–9) and is accepted to be a major factor for chronic atrophic gastritis (CAG),(5) a precursor lesion for stomach cancer.(10)
We here report the results of an ecological study of stomach cancer with reference to H. pylori infection and pepsinogen tests as a marker of CAG,(11,12) along with smoking habits and excretion of sodium and potassium(13) as markers of intake of salt or salted foods, and vegetables and fruit, respectively.(14) The study took place in...