Gastroenterological Cancer Studies

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Gastric Cancer Gastric cancer (GC) is thought to arise from a series of progressive changes, with transformation of normal mucosa to chronic atrophic gastritis (CAG), intestinal metaplasia (IM), dysplasia (DYS) and eventually cancer. Previous work conducted in a cohort study of 3,400 subjects selected at random with precancerous gastric lesions in Linqu County, Shandong Province, China revealed a strong relationship between risk of GC and severity of baseline lesions. Recent work has focused on factors that influence rates of transition in this cohort. Helicobacter pylori (H. pylori) infection at baseline was a risk factor for progression to DYS/GC after a 4.5-year follow-up (OR=1.8, 95% CI=1.2-2.6). The risk of progression to DYS/GC increased with both frequency and duration of cigarette smoking. In contrast, risk of progression to DYS/GC decreased by 80% (OR=0.2, 95% CI= 0.1-0.7) among persons with 1989-1990 serum ascorbic acid levels in the highest tertile. The OR for blood type A relative to other types was 1.4 (95% CI=1.1-1.7) for DYS and 1.3 (95%CI=1.1-1.5) for IM. The OR associated with parental history of GC was 1.9 (95%CI=1.2-3.0) for DYS. The combined OR associated with blood type A and parental history of GC was 2.6 (95% CI=1.6-4.3) for DYS and 1.5 (95%CI=0.9-2.3) for IM, suggesting that genetic factors play a role in development of precancerous gastric lesions. Evaluation of the impact of repeated endoscopic screens (1989, 1994, and 1999) found no reduction in GC mortality in this high-risk Linqu population. A recent cross-sectional study among 3,288 adults in Linqu County found no evidence to suggest that exposure to pets or other domestic animals during either childhood or adulthood was related to the prevalence of H. pylori infection. However, H. pylori seroprevalence was elevated for: infrequent hand washing before meals (OR=1.7, 95%CI=1.0-3.0), sharing a bed with more than two people (OR=2.3, 95%CI=1.3-4.2), washing/bathing in a pond or ditch (OR=1.5, 95%CI=1.0-2.4), and medium (OR=1.6, 95%CI=1.3-2.0) and low (OR=2.3, 95%CI=1.9-2.9) compared to high village education level, and reduced for never being married or being divorced (OR=0.4, 95%CI=0.2-1.0). These findings suggest that person-to-person transmission is the most plausible route of H. pylori infection in this rural Chinese population, but waterborne exposures deserve further investigation. The prevalence of H. pylori in general and CagA+ strains in particular as determined by 13C-UBT was compared among children aged 3-12 years in Shandong Province, China in areas at high (98 children in Linqu County) and low risk (101 children in Cangshan County) of GC . The percent of H. pylori-positive children was nearly three times higher among children in Linqu (69.4%) than in Cangshan (28.7%) and may contribute to the large differential in GC rates in these neighboring populations. Among children positive for 13C-UBT, the proportion of CagA+ strains was 88.5% in Linqu and 81.3% in Cangshan. Colon Cancer There was little evidence of an association between intake of fruits or vegetables and risk of colorectal cancer in an analysis of 477 colorectal cancer cases diagnosed among 45,486 women who completed a 62-item NCI/Block food-frequency questionnaire as part of the Breast Cancer Detection Demonstration Project Follow-up Study. Esophageal Cancer Data from a population-based case-control study of squamous cell esophageal cancer among 347 male cases and 1354 male controls from Atlanta, Detroit, and New Jersey found significantly elevated ORs for subjects with annual incomes less than $10,000 versus incomes of $25,000 or more (OR=4.3, CI=2.1-8.7 for whites; OR=8.0, CI=4.3-15.0 for blacks). The combination of all four major risk factors: low income, moderate/heavy alcohol intake, tobacco use, and infrequent consumption of raw fruits and vegetables, accounted for almost all of the squamous cell esophageal cancers in whites (98%) and blacks (99%) and for 99% of the excess incidence among black compared to white men.