Markers for Early Detection of Prostate Cancer

In the U.S., screening by prostate-specific antigen (PSA) is widespread and considered to be an effective early detection screen for prostate cancer although there are some problems associated with its use. Only about 30-40% of men with elevated PSA are diagnosed with cancer on initial biopsy. The other 60-70% are diagnosed with either benign prostatic hyperplasia or low-or high-grade prostatic intraepithelial neoplasia (LGPIN or HGPIN). Due to their persistent elevated PSA levels, men undergo repeat biopsies where many are subsequently diagnosed with cancer (the false negative rate for biopsies with pathological diagnoses of benign or LGPIN has been reported to be 13-19% and for HGPIN from 50-70%). We propose to conduct a pilot study to evaluate whether (i) the addition of molecular markers (e.g., tumor-specific gene methylation of GSTPI, CD44, Annexin II, and Caveolin 1) detectable in serum and/or urine sediments after prostatic massage can improve the prediction of prostate cancer and (ii) addition of tumor-specific gene methylation detectable in core-needle biopsy specimens can improve the sensitivity of core-needle biopsy in the diagnosis of prostate cancer among patients screened at two Urology clinics located at Howard University, Washington, DC and Madigan Army Medical Center, Tacoma, WA. Preliminary studies have shown detection of hypermethylated genes in urine sediments after prostatic massage in men with elevated PSA (greater than 4ng/ml) improved the specificity of PSA from 73% to 98%. Further, DNA hypermethylation of tumor-specific genes was also identified in serum. In our laboratory, we have developed assays for evaluating DNA hypermethylation of several genes shown to be important in prostate carcinogenesis. These assays are highly sensitive (able to detect down to about 20 tumor cells with methylated DNA) and specific (can distinguish methylated from normal DNA from in a ratio of 1 tumor cell in 10,000 normal cells), and could serve to add value to current prostate cancer screening modalities.