Publication list via PubMed

Overview

My research has been directed towards the identification of lifestyle and environmental factors related to cancer risk. Particular interest has been focused on the role of nutrition, infectious diseases, and serum biomarkers in the etiology of site-specific cancers. Current projects include a prospective cancer study of serum biomarkers in a Japanese-American cohort, a multiethnic case-control study of gastric cancer, and a multiethnic cohort study of cancer.

Current Research

Many years ago, migrant studies in Hawaii helped to determine that environmental exposures strongly affected cancer risk. To pursue this lead, we are conducting a long-term prospective study of cancer among Japanese-Americans. Some recent findings include the following: 1) colonization by an Helicobacter pylori bacteria strain with the cagA gene is associated with a greater risk for gastric cancer; 2) cigarette smoking may explain the apparent protective effect of individual and total carotenoids against urinary bladder cancer; 3) there is a weak positive association of insulin-like growth factor I with colon cancer, but not with rectal cancer.

We are presently doing a multiethnic, population-based, case-control study of gastric cancer. The goal is to determine whether Helicobacter pylori infection, a low serum pepsinogen I/II ratio, a high salt or nitrite intake, a low intake of specific fruits and vegetables, and a family history of gastric cancer, separately or in combination, better identifies subjects at high risk for this disease. Many past epidemiologic studies of gastric cancer have investigated these and other factors separately, so it has been difficult to determine their combined effect on gastric cancer risk.

We are conducting a large multiethnic cohort study of cancer in Hawaii and Los Angeles. During the period from 1993 to 1996, baseline questionnaire data were collected on over 215,000 study participants. They will be followed for a number of years to identify incident cases of specific types of cancer, including colorectal cancer. We will investigate in detail the association of this cancer with medical history, body mass index, cigarette smoking history, alcohol intake, use of vitamin supplements, medication history, physical activity, and diet. In addition, we hope to study the relation of colorectal cancer to plasma folate, serum 25-hydroxyvitamin D, serum 1,25-dihydroxyvitamin D, urinary isothiocyanates (reflecting intake of cruciferous vegetables), and plasma insulin-like growth factors.