The objectives of this project are to identify and describe environmental and host determinants of cancer through analytical, biostatistical and epidemiologic approaches, including studies in areas at high risk of cancer, particularly case-control studies of specific cancers. Data collection was completed for a case-control study of renal cancer in Minnesota, which leads the nation in rates of this malignancy. The study will evaluate the role of diuretics, widely-prescribed medications recently linked to renal tumors in experimental animals. A parallel international investigation in northern Europe and Australia is also nearing completion. Data analyses from a large multi-center study of oral cancer revealed reduced risks among consumers of vitamin E supplements. Follow-up of the patients to assess reasons for a high frequency of second primary cancers is underway. A new study was launched to evaluate reasons for the exceptionally high rates of oral cancer in Puerto Rico. In studies in high-risk areas overseas, fruit, fresh vegetables, and vitamins C and E intakes were associated with reduced risk of both cardia and other stomach cancers in Italy, and serum pepsinogen but not Helicobacter pylori antibody levels were correlated with the geographic variation in stomach cancer rates within Italy. Plans were initiated for parallel case-control studies of stomach cancer in Poland and in Polish Americans in Chicago. In China, vitamin/mineral intervention trials continued in Linxian, a rural Chinese county with the world's highest rate of esophageal cancer, as did an investigation of the determinants of gastric precancerous lesions and their rates of transition to stomach cancer in Shandong Province. Cigarette smoking was found to be a principal determinant of transitions to gastric dysplasia. Occupational studies in China found a weak association between silica exposure and lung cancer and an inverse relation between colon cancer and physical activity. Data collection for a large cohort of benzene-exposed workers drew near completion.
