CANCER EPIDEMIOLOGY IN ADVENTISTS--A LOW RISK GROUP

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The goals of this research are to provide strong evidence about the possible effects of certain dietary variables on risks of three of the most common cancers (breast, prostate and colon). The selected dietary variables are of great interest as the popular press widely promotes their use, but without clear evidence. They are a) soy isoflavones; b) vitamin D, calcium intake and sunlight exposure; and c) Long chain unsaturated fatty acids (especially linolenic acid). We take the opportunity to study a special population that will add unusual clarity to these investigations. During Years 01-04 of this research a large cohort of Seventh-day Adventists has been established (85,000 of the anticipated 105,000 subjects are now enrolled). More than half of Adventists eat soy at levels seen elsewhere only in the Far East, and estimates of soy intake correlate highly with urinary isoflavones. They also have an unusually wide range of calcium consumption, and the population, who are drawn from all 50 states and Canada, spans of wide range of latitudes and hence sunlight exposure. Nearly half of the population are vegetarian, and many eat dairy products, nuts, seeds and soy, these providing a wide range of dietary linolenic and other long-chain unsaturated acids. These attributes lend power to statistical analyses. A large calibration/validation study of 1000 subjects is being established to support these analyses. During the next 5 years approximately 1650 new cancers at the selected body sites will be identified. With support from the North American tumor registry association, we will computer-match with all U.S and Canadian tumor registries using methods that are uniform and pilot-tested. This has not previously been accomplished and our methods and experience will be useful for other investigators. A new research emphasis in the next funding period is the modification of dietary effects on these cancers, by genes. This work will focus on genetic variants of known functional importance that are relevant to one of the three areas of dietary emphasis listed above. Starting Year 06 four very experienced investigators will collaborate with the Loma Linda research team for this purpose. Using a well-tested plan we will establish a bio-repository to support this new emphasis. Blood will be obtained from 50,000 subjects, subcutaneous fat aspirates from 33,000 and saliva samples from 30,000. At least one biomarker will be obtained from more than 80,000 subjects. Finally, 25-30% of this cohort are black (African-American), and the research questions will be investigated in the whole population as well as separately in this group. Black Adventists have broadly similar dietary trends, but for unknown reasons this minority population has a much greater incidence certain cancers. In summary, we have established a large cohort spanning both the U.S. and Canada from a uniquely informative population. As originally planned it is during the coming Years 06-10 that this outstanding resource will provide answers to the questions posed.