Zinc-Based Early Detection of Prostate Cancer

DESCRIPTION (provided by applicant): In Phase I we showed that our measurement of free zinc in expressed prostatic fluid is a promising clinical indicator of prostate cancer. Indeed, in our two pilot studies and one prior published study, prostatic fluid z inc scores gave areas under the receiver operating curve (AUROC) of .79, .92, and .99 for detecting biopsy-confirmed prostatic adenocarcinoma. Our test is non-invasive, requiring only a few drops of prostatic fluid obtained from the urethral meatus during a rectal prostate examination with brief prostate massage. The zinc measurement is fast, cheap, easy, and exquisitely accurate. Our Phase II study has two components. In Study IIA we will increase our sample size to better estimate the sensitivity and spec ificity of our test. We will collect samples of prostatic fluid from a carefully selected sample of approximately 100 men expected to have prostate adenocarcinoma and approximately 100 men expected to be cancer free. Upon histopathological confirmation of adenocarcinoma or the absence of adenocarcinoma in all men, a receiver operating curve analysis will be conducted to determine the sensitivity, specificity and overall area under the curve (AUROC) for the detection of adenocarcinoma by the measurement of z inc in prostatic fluid. This study will show how useful the zinc test is for detecting prostate cancer. The subjects in this study will be (i) men scheduled for prostatectomy (ii) men scheduled for cysto-prostatectomy (iii) men scheduled for saturation (64 core) needle biopsy and (iv) men scheduled for conventional biopsy. In Study IIB we will establish which prostatic disease conditions are accompanied by the loss of zinc sequestering and secretion. Thus, we will take tissue sections from the prostate glan ds of the subjects in Study IIA, stain them with HandE and (in some cases) antibodies to disease- defining proteins. Regions with specific prostatic pathology such as PIA (proliferative inflammatory atrophy), PIN (prostatic intraepithelial neoplasia) or ad enocarcinoma will be marked on digital images of the sections, then adjacent sections will be imaged in X-RAY fluorescence and zinc histofluorescence microscopy to show the distribution of elemental and free zinc , respectively. Comparison of the classical histology with the zinc maps by digitally superimposing them will show how zinc sequestration (and therefore secretion) changes in each of the different types and stages of pathology. Data in the literature indicate that zinc sequestration and secretion a re suppressed in PIN and suppressed in healthy-appearing acini that are near an adenocarcinoma, suggesting a field effect. If confirmed by our work, this would explain how even relatively small adenocarcinomas markedly suppress zinc secretion of the gland. Every year in the US about 1,500,000 prostate biopsies are done, revealing only about 300,000 cancers. Still, about 30,000 men die from cancers too advanced for effective treatment. We believe our zinc test could allow earlier and more certain detection o f potentially aggressive cancers, thus saving lives. PUBLIC HEALTH NARAVTIVE: This Phase II SBIR is designed to determine the sensitivity and specificity of a zinc test for prostate cancer. The test measures zinc in massage-expressed prostatic fluid, and i t only takes about 60 sec to get the fluid and about 60 sec to make the measurement on a table-top, 5000 instrument. The test is intended to supplement other tests, including the PSA and DRE. Because the zinc falls in cancer but does not fall in BPH, the zinc tests has the potential to distinguish these two conditions.