PSA AS AN INTERMEDIATE MARKER FOR PROSTATIC CANCER

前列腺癌仍然是癌症相关死亡的主要原因 在美国 确定预防疾病的方法 并建立其早期诊断对于减少 前列腺癌的死亡率，因此至关重要。 这个项目将测试的假设，前列腺系列测量 特异性抗原（PSA）是前列腺癌的中间标志物。 它还将在一对正在进行的随机双盲癌症患者中进行测试， 使用微量营养素硒（Sc）的预防试验，假设 硒的补充可以降低 前列腺特异性抗原升高或前列腺癌 本研究的设计是双向的。 回顾性部分 将测量1,000名男性的冷冻血清样本中的PSA水平。 正在进行的癌症预防试验。 将确定三个PSA水平 和具有阳性PSA水平的受试者（PSA>4.0 ng/ml或年PSA> 4.0 ng/ml）。 阳性趋势>0.75毫微克/毫升）将转介跟进， 将获得相应的文件。 前瞻性部分将包括两个队列： 来自低Sc地区的两项癌症预防试验的男性 美国 这两个群体的结合将提供广泛的 血浆Sc水平的分布。 第一批将有半年一次的 PSA，Sc，用于血浆Sc水平的宽分布。 第一个队列 将有半年PSA，Sc，微量营养素，睾酮， 催乳素测量。 PSA水平为阳性的受试者将 提交后续行动，并将获得相关文件。 估计250例PSA水平升高和101例前列腺增生 癌症将在本研究过程中报告。 这些数字将 为该项目提供统计能力，以检测30%的减少， PSA的中位失败时间和42%的中位时间减少， 在80%把握度的双尾检验中， α = 0.05。

Prostate cancer continues to be a leading cause of cancer-related death in the United States. Identifying the means for preventing the disease and establishing its earlier diagnosis are essential for reducing mortality from prostate cancer and are, therefore, of utmost importance. This project will test the hypothesis that serial measurement of prostate specific antigen (PSA) is an intermediate marker for prostate cancer. It will also test, in a pair of ongoing randomized, double-blind cancer prevention trials using the micronutrient selenium (Sc), the hypothesis that Se supplementation reduces the incidence of either serially increasing PSA levels or prostate cancer. The design of this study is ambi-directional. The retrospective portion will measure PSA levels in the frozen serum samples of 1,000 men in the ongoing cancer prevention trials. Three PSA levels will be determined and subjects with positive PSA levels (a PSA of >4.0 ng/ml or an annual positive trend of >0.75 ng/ml) will be referred for follow up and the resultant documentation will be obtained. The prospective portion will consist of two cohorts:with a total of 1,000 men from the two cancer prevention trials from the low Sc areas of the U.S. The combination of these two cohorts will provide for a wide distribution of plasma Sc levels. The first cohort will have semi-annual PSA, Sc, for a wide distribution of plasma Sc levels. The first cohort will have semi-annual PSA, Sc, micronutrients, testosterone, and prolactin measurements. Subject with positive PSA levels will be referred for follow up and the resultant documentation will be obtained. An estimated 250 cases of elevated PSA levels and 101 cases of prostate cancer will be reported in eh course of this study. These numbers will afford this project the statistical power to detect a 30% reduction in the median time to failure for PSA and a 42% reduction in median time to failure for prostate cancer, in a two-tailed test at 80% power and an alpha=.05.