| Budget Amount *help |
¥13,400,000 (Direct Cost: ¥13,400,000)
Fiscal Year 2005: ¥5,500,000 (Direct Cost: ¥5,500,000)
Fiscal Year 2004: ¥7,900,000 (Direct Cost: ¥7,900,000)
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| Research Abstract |
Helicobacter (H) pylori infection is considered to be not only a risk factor for peptic ulcer but also a risk factor for chronic atrophic gastritis (CAG), a precursor condition of gastric cancer. By examining the association between CAG and its risk factors including H.pylori infection among Asian immigrants in the Seattle area in the US and by comparing those risk factors between Seattle and Japan, it is hoped to elucidate our understanding of etiologic mechanism of CAG leading to gastric cancer. About 1,000 immigrants including Japanese, Koreans, Vietnamese, Chinese and Filipinos were recruited through churches and community centers. Screening was conducted by collecting blood samples and self-administered questionnaires on medical history, diet and lifestyle. H.pylori infection and CAG were determined by the E plate 'Eiken' Disk H.pylori antibody method and by the E plate 'Eiken' Disk PG I ＆ II method, respectively (Eiken Chemical Co., Tokyo) by using four drops of blood taken by fi
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nger prick.
As for the Japanese immigrants (or Japanese Americans), we invited only those with CAG-negative in their 1994 serum. Out of 196 persons 4 cases became positive in pepsinogen levels or CAG-positive and resulted in 2% of CAG incidence for the 10-year period (from 1994 to 2004).
Age-adjusted prevalence rates of H.pylori infection were 26.0% for Japanese immigrants (based on their 1994 serum), 26.3% for Filipino immigrants, 36.1% for Chinese immigrants, 39.2% for Korean immigrants, 41.3% for Vietnamese immigrants and 70.6% for native rural Japanese (based on their 1989 serum). Age-adjusted prevalence rates of CAG were 2.2% for Filipino immigrants, 4.6% for Chinese immigrants, 6.3% for Vietnamese immigrants, 7.6% for Koreans immigrants, 11.6% for Japanese immigrants (based on their 1994 serum) and 34.3% for native rural Japanese (based on their 1989 serum).
Odds ratios (OR) of CAG for persons with H.pylori infection were significantly elevated for all groups except Filipino immigrants (OR=2.8) : 4.7 for Chinese, 7.8 for native rural Japanese, 8.9 for Vietnamese immigrants, 10.6 Japanese immigrants and 15.6 for Korean immigrants after adjusting for age, sex, stomach diseases, smoking and drinking. These results suggest that H.pylori infection plays a critical role in leading to chronic atrophic gastritis and then gastric cancer and that H.pylori and pepsinogen screening is a valuable method to identify individuals with an increased risk for developing gastric cancer.
Results of multiple logistic regression analysis showed that in addition to significant association of CAG with aging and H.pylori infection greater than 20-year residency in Japan among Japanese immigrants as compared with none or less than a year residency had a significantly elevated odds ratio (4.53), implying that some unknown environmental factors in Japan possibly elevate risk for developing CAG and gastric cancer. Also, it is interesting to see that the logistic regression model of 4 Seattle Asian immigrant groups combined had significant odds ratios of CAG for most of the risk factors : females (0.33), ages 65-74 (2.44), current drinkers (0.20), ex-and current smokers (0.07), having GI illness (6.19), family history of gastric cancer (7.91), and H.pylori infection (5.86). Thus, while H.pylori infection had dominant effects on development of CAG in both native Japanese in Japan and Japanese immigrants (mostly 2nd and 3rd generation) in Seattle, other risk factors might equally have affected development of CAG among other Asian immigrants. Less
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