Biography

Dr. Chow received a Ph.D. in epidemiology from the University of Washington School of Public Health. She was on the faculty at Emory University before joining the NCI in 1991. Dr. Chow currently serves on the editorial boards for the American Journal of Epidemiology and Cancer Epidemiology, Biomarkers and Prevention. Dr. Chow's research focuses on environmental and lifestyle risk factors associated with kidney and gastrointestinal cancers. She is an elected member of the American Epidemiological Society.

Research Interests

Variations in cancer incidence rates over time usually are related to changes in the prevalence of environmental risk factors in the population. Similarly, variations in incidence rates across geographic regions may reflect differences in exposure patterns. It is important to study cancers that are rapidly increasing in incidence or that have diverse incidence patterns in various populations for etiologic clues and preventive strategies. Opportunities to pursue these research objectives are particularly feasible when a broad range of exposures can be evaluated to enhance assessment of risk and dose response relations.

Gastric and Esophageal Adenocarcinomas

Stomach cancer is the second most common malignancy worldwide, even with declines in incidence over the past few decades. Incidence rates vary substantially among populations, with generally high rates in East Asia, tropical South America, and Eastern Europe, and low rates in western countries. Since Poland has among the highest gastric cancer incidence in Europe, we conducted a case control study in Warsaw to identify risk factors and prevention measures. Our initial analyses revealed that risks are elevated among smokers and those reporting a family history of stomach cancer in first degree relatives. We also found that pro inflammatory genotypes of the cytokine interleukin 1 loci increased both the risk of chronic hypochlorhydric response to Helicobacter pylori infection and the risk of gastric cancer. Ongoing analyses are examining risk in relation to other environmental and genetic factors.

Adenocarcinoma of the esophagus is among the fastest rising malignancies in the United States and Western Europe. Rates are also increasing substantially for adenocarcinoma of the gastric cardia. To pursue earlier leads and clarify risk factors for these tumors, we conducted a collaborative population based case control study with investigators at Columbia University,

Fred Hutchinson Cancer Research Center, and Yale University. Analyses thus far have confirmed our earlier observation that individuals with long standing gastroesophageal reflux disease are at increased risk of esophageal adenocarcinoma, whether or not the symptoms are treated with H2 blockers or antacids. While use of medications that relax the lower esophageal sphincter was not related to risk in general, our data suggest that long term use of certain asthma drugs may increase risk of esophageal adenocarcinoma. We are continuing to evaluate other exposures (e.g., occupational and dietary), family cancer history, genetic polymorphisms, and effect variation by tumor mutation type. Other analyses are examining environmental and host factors that may predict patient prognosis.

Member of the DCEG Upper Gastrointestinal Cancers Research Group

Renal Cell Carcinoma

Recent clinical surveys revealed that incidental detection of renal cell carcinoma is rising, partly because of increased use of imaging procedures, such as ultrasonography, computed tomography, and magnetic resonance imaging. To clarify the pattern of rising trends of renal cell cancer, we examined data from the NCI Surveillance, Epidemiology, and End Results program. Between 1975 and 1995, rates increased two-to-three percent among whites and four or more percent among African-Americans. Increases were greatest for localized tumors, but were also seen for more advanced and unstaged tumors. In contrast, incidence rates for renal pelvis cancer have declined or remained stable. These results suggest that the increasing detection of presymptomatic tumors by imaging procedures does not fully explain the upward incidence trends of renal cell cancer. Ongoing analyses are examining the international incidence patterns of kidney cancer, as well as age period cohort patterns in incidence and mortality rates among Caucasian and African-Americans in this country.

We previously observed that obesity and hypertension increase the risk of renal cell cancer. The increasing prevalence of these conditions in the United States may be contributing to the rising incidence of this tumor. To quantify the risk and evaluate the effects of changes in weight and blood pressure, we analyzed data from a cohort study of Swedish male construction workers who underwent physical examinations from 1971 to 1992. We found that even small excesses in weight or blood pressure may independently increase the long term risk of renal cell cancer, while reduction in blood pressure may lower the risk. We are planning further epidemiologic studies to examine other potential genetic and environmental risk factors, including dietary and occupational exposures, and to identify reasons for the higher and more rapid increases in incidence among African-Americans than Caucasians in the United States.

Cancer in Women: Occupational and Environmental Risk Factors

Little is known about occupational cancer risks among women. A limited number of studies suggest that women are susceptible to the same carcinogens as men, but their risks may vary due to hormonal, metabolic, genetic, or other gender differences. We are evaluating this issue in a collaborative study with investigators at Vanderbilt University and the Shanghai Cancer Institute. The study is assessing a number of cancer risk factors, with special attention to occupational and environmental exposures, in a cohort of 75,000 women in Shanghai, China. Environmental exposures and biomarkers of genetic susceptibility will be examined in blood, urine, and buccal cell specimens. The study will become over time an invaluable data resource for identifying carcinogenic exposures and gene environment interactions in women.

Keywords

esophageal adenocarcinoma, gastric adenocarcinoma, gastroesophageal reflux disease, Helicobacter pylori, hypertension, interleukin 1, obesity, occupation, renal cell carcinoma, stomach cancer, women

Collaborators

DCEG Collaborators

• Christian Abnet, Ph.D.; Michael Cook, Ph.D.; Sandy Dawsey, Ph.D.; Susan Devesa, Ph.D.; Neal Freeman, Ph.D.; Melissa Friesen, Ph.D.; Barry Graubard, Ph.D.; Jonathan Hofmann, Ph.D.; Bu-Tian Ji, M.D., Dr.P.H.; Farin Kamangar, M.D., Ph.D.; Sara Karami, Ph.D.; Qing Lan, M.D., Ph.D., M.P.H.; Linda Liao, Ph.D.; Morton Lineman, M.D.; Lee Moore, Ph.D.; Mark Purdue, Ph.D.; Charles Rabkin, M.D.; Nathaniel Rothman, M.D., M.P.H.; Rashmi Sinha, Ph.D.; Phil Taylor, Ph.D.; Sholom Wacholder, Ph.D.; Mary Ward, Ph.D.; Kai Yu, Ph.D.

Other Scientific Collaborators

• Andrea Baccarelli, M.D., Ph.D.; Harvard University, Cambridge, MA
• Antonia Calafat, Ph.D.; Center for Disease Control and Prevention, Atlanta, GA
• Douglas Corley, M.D., Ph.D.; Kaiser Permanente, Oakland, CA
• Faith Davis, Sc.D.; University of Illinois at Chicago, Chicago, IL
• Emad El-Omar, M.D., Ph.D.; University of Aberdeen, Aberdeen, Scotland
• Lawrence Engel, Ph.D.; Marilie Gammon, Ph.D.; University of North Carolina, Chapel Hill, NC
• Lifang Hou, M.D., Ph.D.; Northwestern University, Chicago, IL
• Yu-Tang Gao, M.D.; Shanghai Cancer Institute, Shanghai, China
• Jolanta Lissowska, Ph.D.; Maria Sklodowska Curie Memorial Cancer Center, Warsaw, Poland
• Ginger Milne, Ph.D.; Xiao Ou Shu, M.D., Ph.D.; Vanderbilt University, Nashville, TN
• Harvey Risch, M.D., Ph.D.; Yale University, New Haven, CT
• Kendra Schwartz, M.D.; Wayne State University, Detroit, MI
• Paul Turner, Ph.D.; University of Leeds, Leeds, England
• Thomas Vaughan, M.D.; Fred Hutchinson Cancer Research Center, Seattle, WA
• David Whiteman, M.D., Ph.D.; Queensland Institute of Medical Research, Herston, Australia
• Weimin Ye, M.D., Ph.D.; Karolinska Institute, Stockholm, Sweden