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 并确定其早期诊断对于减少 因此，前列腺癌的死亡率是至关重要的。 这个项目将检验这样一种假设，即对前列腺的连续测量 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中进行测试 使用微量营养素硒(SC)的预防试验，假设 补硒可连续降低这两种疾病的发生率。 PSA水平升高或前列腺癌。 本研究的设计是双向的。回顾部分 将测量1000名男性冰冻血清样本中的PSA水平 正在进行的癌症预防试验。将确定三个PSA水平 和PSA水平阳性的受试者(PSA为4.0 ng/ml或每年 (&gt；0.75 ng/ml)的阳性趋势将被转诊为后续行动，并 将获得最终的文件。 未来的部分将由两个队列组成：总共1000人 来自美国低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。第一批将每半年一次 PSA、SC、血浆SC水平分布广泛。第一批人 将每半年进行一次PSA、SC、微量营养素、睾丸素和 催乳素测量。PSA阳性的受试者将是 将提交后续行动，并将获得结果文件。 估计有250例PSA水平升高和101例前列腺癌 癌症将在这项研究的过程中被报道。这些数字将 为该项目提供统计能力，以检测到 PSA的中位故障时间和中位故障时间缩短42% 前列腺癌失败，在80%功率的双尾测试中， 阿尔法=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.