varies by racial or ethnic group. A population-based, case-control study in North Carolina focuses on the causes of breast cancer among African-American and white women who live in suburban and rural areas of eastern and central North Carolina. The study integrates epidemiology and molecular biology to explore risk factors and possible gene-environment interactions as causes of cancer. Other studies are aimed at understanding differences in breast cancer incidence among younger (under age 40) African-American and white women, diet and risk of breast cancer among Asian-American women, and whether racial or ethnic variations in breast cancer incidence and prognosis are attributable to various exogenous mutagens.

Cervical Cancer

The incidence of cervical cancer is disproportionately high among African-American, Hispanic, and some Asian-American women. NCI supports case-control studies in Jamaica to understand the etiologic risks for cervical cancer associated with HPV, HIV, and HTLV, as well as a large study in Costa Rica that examines genetic susceptibility markers and nutrition to assess why common HPV infections sometimes persist and progress to cervical cancer. Both are Category I studies.

Nasopharyngeal Cancer

NCI-supported scientists are studying the role of a range of environmental, lifestyle, and genetic factors in the development of nasopharyngeal cancer (NPC), the incidence of which is particularly high in Southeast Asia and among individuals of Chinese descent. A case-control study in the Philippines has revealed a strong link between occupational exposures to chemicals (e.g., formaldehyde), smoking, and other environmental risk factors and NPC. Scientists are also examining the role of oncogenes and tumor suppressor genes in the pathogenesis of NPC. The interplay of genetic factors and environmental exposures is also being assessed in a family-based study recently initiated in Taiwan. Finally, NCI is also supporting a study of 60,000 Chinese men in Singapore to investigate the relationship between diet, particularly ethnic foods such as salted fish, and NPC. These studies have been classified as Category I and II studies.

Oral and Pharyngeal Cancers

DCEG staff are investigating the relationship between smoking and alcohol consumption and oral and pharyngeal cancers, the rates of which are 30 to 100 percent higher among African Americans than whites. When the rates for African-American and white nonsmokers and nondrinkers are compared, they are nearly equivalent. These relationships are being studied further in a case-control study in Puerto Rico, an area with high rates of oral and pharyngeal cancers. This study has revealed a greater risk for oral cancer with increasing alcohol



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