How to improve prostate biopsy detection of prostate cancer

Detecting prostate cancer by intracellular macrophage prostate-specific antigen (PSA): a more specific and sensitive marker than conventional serum total PSA

BACKGROUND

Serum prostate-specific antigen (PSA) is a standard method and a widely used marker for prostate cancer, but it has a poor specificity for early detection. Herein we demonstrate that intracellular macrophage PSA (imPSA) enables screening and differentiation between benign and malignant prostate disease.

MATERIALS AND METHODS

The efficacy of intracellular macrophage PSA in circulating and tissue macrophages was therefore investigated in a double-centre study of 38 prostate cancer patients and 36 healthy controls by fluorescent-activated cell sorting analysis and immunohistology.

RESULTS

Both methods uncovered the existence of PSA-positive macrophages specific for patients with prostate cancer. In addition, we demonstrate the superiority of our new test over standard serum total PSA in a blinded double-centre trial. ImPSA had a marked higher sensitivity and specificity than serum total PSA (imPSA: sensitivity 92%, specificity 92%, positive predictive value 92%; serum total PSA: sensitivity 79.5%, specificity 87.5%, positive predictive value 26.8%).

CONCLUSION

In this study, we demonstrate that imPSA is a new prostate cancer screening method that is highly sensitive and more specific than standard PSA testing.

Efficacy and tolerability of the dual 5α-reductase inhibitor, dutasteride, in the treatment of benign prostatic hyperplasia in African-American men

The efficacy and tolerability of dutasteride (0.5 mg daily for 2 years) in African-Americans (n=161), compared with Caucasians (n=3961), was assessed in a post hoc analysis of data from three Phase III clinical trials. Dutasteride significantly reduced serum dihydrotestosterone levels by >90% and significantly improved subjective (symptom score) and objective (prostate volume, peak urinary flow rate, risk of benign prostatic hyperplasia-related surgery and acute urinary retention) outcomes in both African-Americans and Caucasians. For all efficacy measures, there was no statistically significant treatment-by-race interaction and dutasteride was well tolerated in both racial groups. Therefore, dutasteride demonstrated similar efficacy and safety profiles in African-Americans and Caucasians.

Ability of PSA-positive circulating macrophages to detect prostate cancer

BACKGROUND

Prostate-specific antigen (PSA) is a widely used serum marker for prostate cancer, but has a poor specificity for early detection at levels below 10 ng/ml, because it can also result from benign conditions. Our aim was to determine the frequencies of circulating PSA+ macrophages in a blinded study and to examine the suitability of this new method for differentiating between benign and malignant prostate disease.

METHODS

Between October 2002 and February 2003, 126 patients undergoing transrectal biopsy were enrolled in this study. Peripheral blood macrophages were stained for intracellular content of PSA in all patients. Ten patients' peripheral blood mononulear cells (PBMCs) were also supplementarily stained for cytokeratin (CK) and epithelial membrane antigen (EMA). Macrophages were analysed by flow cytometry. Patients were grouped according to their biopsy histology and bone scan results.

FINDINGS

Based on histological data, patients were classified as having no evidence of malignancy (NEM) (n = 59), prostatitis (n = 20), or localised prostate cancer (n = 37). Significantly higher levels of circulating PSA+ macrophages were found in prostate cancer compared to benign conditions. Calculating a 2% cut-off level enabled the detection of localised prostate cancer with 89% sensitivity and 80% specificity. In a subset of patients (65%) with a serum PSA below 4 ng/ml and confirmed prostate cancer, the percentage of PSA+ macrophages was significantly higher compared to NEM and prostatitis. Macrophages of ten patients tested with prostate cancer contained significantly higher amounts of PSA, EMA, and CK compared to ten with NEM.

INTERPRETATION

Intracellular PSA in combination with CK and EMA can be found in permeabilized blood macrophages, indicating phagocytosis of complete cancer cells. This study further suggests, that this new method might be suitable for differentiating between prostate cancer and benign conditions especially in patients with low serum PSA.

Measurement of Intracellular Versus Extracellular Prostate-Specific Antigen Levels in Peripheral Macrophages: A New Approach to Noninvasive Diagnosis of Prostate Cancer

Although prostate-specific antigen (PSA) is a useful screening marker in prostate cancer, it has limited specificity. Previously it was shown that the amount of surface-bound PSA present on circulating macrophages was different between patients with localized prostate cancer and those with metastatic prostate cancer. It was recently demonstrated that intracellular PSA in macrophages can be measured by flow cytometry. In the context of searching for a noninvasive, highly reliable method for prostate cancer diagnosis, we assessed the extent to which extracellular (ie, surface-bound) and intracellular PSA-positive macrophages might differentiate patients with benign versus malignant prostatic disease. In a pilot study, the levels of complexed, surface-bound, and intracellular PSA were measured in 25 patients with elevated serum PSA values and histologically confirmed disease. In this group, no significant differences for serum PSA and complexed PSA levels, respectively, could be detected among patients with benign prostatic hyperplasia, prostatitis, and prostate cancer. Significant differences, however, were detected in intracellular PSA, although not in surface-bound PSA, among the 3 groups of patients. Intracellular PSA was measured prospectively in a second cohort of 189 patients who had a transrectal biopsy because of a serum PSA constellation suspicious for prostate cancer. In the expanded cohort, highly significant differences in intracellular PSA were observed between benign and malignant disease of the prostate, even in patients with serum PSA level<4 ng/mL. Screening of serum PSA alone or in combination with complexed PSA does not clearly distinguish patients with prostate cancer from those with prostatitis or benign prostatic hyperplasia. Macrophage intracellular PSA might represent a more.