This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.Prostate cancer is a major public health problem, accounting for more than 230,000 cases and more than 30,000 deaths per year in the US. The best tool for detecting prostate cancer early, and therefore beginning treatment before the disease progresses significantly, is the common prostate specific antigen or PSA test. This test uses a simple blood sample to measure the amount of PSA circulating. High levels of PSA indicate possible cancer. More than 45 million PSA tests are done worldwide each year because this is an effective diagnostic and screening tool that has saved many lives. However, there are still problems with the PSA test. Most importantly, about 25% of men with elevated PSA levels do not have cancer, and about one quarter of men with prostate cancer do not have high PSA levels, and are therefore not detected by the current PSA test.Clinicians have been forced to conclude that although blood PSA testing is a valuable and important tool, we still need to learn more about the causes of individual variation in PSA levels. The data show that cancer is one reason for high PSA levels, but there must be other reasons as well. In addition, there must be some reason why some men with cancer do not show high levels. The best hypotheses to explain the variation in PSA levels that is not due to cancer are: A) genetic differences among men influence their PSA levels, separate from cancer, and B) obesity and physiological changes related to obesity also affect PSA levels.The purpose of this pilot study is to investigate baboons as a new animal model to study the causes of individual variation in PSA levels. Baboons are an excellent choice for this because they do not get prostate cancer. As a result, we can study differences in PSA levels without worrying that some animals may have higher than average PSA levels due to early undiagnosed prostate cancer. We will conduct a series of analyses of PSA levels among 250 male baboons. These analyses will tell us whether: a) genetic differences among baboons influence PSA levels, b) age influences baboon PSA as it does human PSA, and c) differences in body fat and obesity among the baboons also influence PSA levels. The results of this pilot study will be important in developing larger research applications to the National Institutes of Health to study this important clinical problem that affects thousands of men in the US each year.
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