Molecular epidemiology of gastric and prostate cancers in people from various racial and ethnic backgrounds

Underserved populations are prone to certain types of cancer. For example, almost two-thirds of the gastric cancer cases worldwide occur in developing countries; specifically, people from East Asia, Eastern Europe, and parts of Central and South America are at high risk. In terms of prostate cancer, African-Americans have 1.6 times the incidence and 2.3 times the mortality than Caucasians. Better understanding of these cancers may help implement preventive and screening measures more efficiently.; This doctoral dissertation comprises three studies focusing on the epidemiology of gastric and prostate cancers in various racial and ethnic populations. The first study (Chapter I) examines the prevalence of Helicobacter pylori infection and socioeconomic status in different generations of Hispanics and non-Hispanic whites, and is based on data from a community-based cohort study in the San Francisco Bay Area. Results from this analysis lend credence to the hypothesis that both household characteristics and birth country environment are important determinants of H. pylori infection, a major risk factor for gastric cancer.; In the second study (Chapter II), complementary DNA microarray technology is used to analyze gastric tissue biopsies from a randomized placebo-controlled trial of H. pylori therapy, conducted in H. pylori -infected patients with preneoplastic conditions in Chiapas, Mexico. By identifying changes of gene expression due to H. pylori eradication, this study sheds light on the molecular pathways to gastric carcinogenesis and their reversibility following H. pylori eradication, this study sheds light on the molecular pathways to gastric carcinogenesis and their reversibility following H. pylori eradication.; The third study (Chapter III) is a prospective, nested case-control study using a cohort of 10,442 young African-Americans and Caucasians to investigate the association between serum steroid hormone levels at young age and subsequent prostate cancer risk. This study provides the first quantitative data on long-term associations between these hormonal factors and subsequent prostate cancer risk in both African-Americans and Caucasians. In addition, it allows evaluation of racial differences in hormone levels in young men.; Taken together, the above-mentioned studies offer insight into the etiology and prevention of gastric and prostate cancers in various racial and ethnic populations. Results from these studies may help physicians determine the most effective screening and treatment options in high-risk populations.