Urinary prostate specific antigen levels: role in monitoring the response of prostate cancer to therapy

Elimination Kinetics of Prostate-Specific Antigen Serum and Urine

The serum half-life of prostate-specific antigen (PSA) was calculated in 66 patients subsequent to radical prostatectomy. Comparing serum half-life to disease outcome in 37 patients after a minimum follow-up of two years, it was found that PSA serum half-life identifies patients with residual disease earlier and more reliably than the presence or absence of detectable PSA levels postoperatively. It is suggested that residual tumor affects the half-life by contributing to the serum level of PSA. When PSA serum half-life was calculated solely in potentially cured patients, we found a half-life of 1.6 days, which is considerably shorter than in previous reports based on patient populations regardless of the outcome of disease in the follow-up.

To elucidate the route of PSA elimination, serial urine PSA levels were determined before and after radical prostatectomy, revealing strong evidence for the assumption that PSA is not eliminated by the kidneys in its unchanged form.

Evaluation of sulfur isotopic enrichment of urine metabolites for the differentiation of healthy and prostate cancer mice after the administration of 34S labelled yeast

Sulfur isotopic enrichment of urine metabolites in healthy and prostate cancer mice using ³⁴S enriched yeast and High Performance Liquid Chromatography coupled to Multicollector Inductively Coupled Plasma Mass Spectrometry (HPLC-MC-ICP-MS) has been evaluated. A 30 weeks experiment (since the eleventh to the fortieth week of life) was carried out collecting the urine of three healthy mice and three transgenic mice with prostate cancer during 24h after a single oral administration of a ³⁴S enriched yeast slurry. The isotopic enrichment of different sulphur metabolites was monitored by coupling a C18 reverse phase HPLC column with a multicollector ICP-MS using a membrane desolvating system. Quantification of sulfur in the chromatographic peaks was carried out by post-column isotope dilution using a ³³S enriched spike. Differences between the ³⁴S enrichment in the urine metabolites of healthy and prostate cancer mice were found from the beginning of the disease. Both populations could be differentiated using a principal component analysis (PCA). Finally, 7 unknown mice were correctly classified in each population using a linear discriminant analysis.

The present and future of prostate cancer urine biomarkers

In order to successfully cure patients with prostate cancer (PCa), it is important to detect the disease at an early stage. The existing clinical biomarkers for PCa are not ideal, since they cannot specifically differentiate between those patients who should be treated immediately and those who should avoid over-treatment. Current screening techniques lack specificity, and a decisive diagnosis of PCa is based on prostate biopsy. Although PCa screening is widely utilized nowadays, two thirds of the biopsies performed are still unnecessary. Thus the discovery of non-invasive PCa biomarkers remains urgent. In recent years, the utilization of urine has emerged as an attractive option for the non-invasive detection of PCa. Moreover, a great improvement in high-throughput “omic” techniques has presented considerable opportunities for the identification of new biomarkers. Herein, we will review the most significant urine biomarkers described in recent years, as well as some future prospects in that field.

Urinary PSA: a potential useful marker when serum PSA is between 2.5 ng/mL and 10 ng/mL

INTRODUCTION

Our objective was to evaluate the usefulness of urinary prostate specific antigen (PSA) in the differential diagnosis of benign prostatic hyperplasia (BPH) and prostate cancer.

METHODS

We undertook a prospective study and obtained informed consent from 170 men. They provided blood samples to measure serum PSA and 50 mL of first-voided urine to measure urinary PSA. Seventy-seven men were diagnosed with BPH; 42 patients had newly diagnosed prostate cancer; and 51 were selected as age-matched control subjects. Data were analyzed using Wilcoxon signed rank tests, receiver operating characteristic (ROC) curves and logistic regression.

RESULTS

Prostate volume was 35 cm(3) and 45 cm(3) (p < 0.05), serum PSA was 9.7 ng/mL and 4.5 ng/mL (p < 0.001) and PSA density was 0.28 and 0.11 (p < 0.01) for prostate cancer and BPH patients, respectively. Overall, urinary PSA was not significantly different, but PSA ratio (urinary:serum) was significantly different at 6.7 and 30.6 (p < 0.001) for prostate cancer and BPH patients, respectively. A subgroup with serum PSA between 2.5 ng/mL and 10.0 ng/mL was selected and urinary PSA was significant: 52.6 ng/mL (n = 29) and 123.2 ng/mL (n = 35) (p < 0.05) for prostate cancer and BPH patients, respectively. PSA ratios were also significant (p = 0.007). ROC curves identified a cutoff for urinary PSA at > 150 ng/mL, with a sensitivity of 92.5%. When comparing prostate cancer patients with age-matched control subjects, serum PSA, urinary PSA and PSA ratio were different (p = 0.004).

CONCLUSION

Our study supports urinary PSA as a useful marker in the differential diagnosis of prostate cancer and BPH, especially when serum PSA is between 2.5 ng/mL and 10 ng/mL. Low urinary PSA and PSA ratios point toward prostate cancer. A urinary PSA threshold of > 150 ng/mL may be used to decrease the number of prostatic biopsies.

Early detection of prostate cancer local recurrence by urinary prostate-specific antigen

PURPOSE

We assessed the role of urinary prostate-specific antigen (uPSA) in the follow-up of prostate cancer after retropubic radical prostatectomy (RRP) for the early detection of local recurrences.

METHODS

We recruited 50 patients previously treated for prostate cancer with RRP and who had not experienced a prostate-specific antigen (PSA) recurrence within their first postoperative year into a cross-sectional laboratory assessment and prospective 6-year longitudinal follow-up study. We defined biochemical failure as a serum PSA (sPSA) of 0.3 μg/L or greater. Patients provided blood samples and a 50-mL sample of first-voided urine. We performed Wilcoxon rank-sum and Fisher exact tests for statistical analysis.

RESULTS

The median sPSA was 0.13 μg/L. The median uPSA was 0.8 μg/L, and was not significantly different when comparing Gleason scores or pathological stages. Of the 50 patients, 27 initially had a nondetectable sPSA but a detectable uPSA, and 11 patients experienced sPSA failure after 6 years. Six patients had detectable sPSA and uPSA initially. Fifteen patients were negative for both sPSA and uPSA, and 13 remained sPSA-free after 6 years. The odds ratio (OR) of having sPSA failure given a positive uPSA test was 4.5 if sPSA was undetectable, but was reduced to 2.6 if sPSA was detectable. The pooled Mantel-Haenszel OR of 4.2 suggested that a detectable uPSA quadrupled the risk of recurrence, independent of whether sPSA was elevated or not. The sensitivity of uPSA for detecting future sPSA recurrences was 81% and specificity was 45%.

CONCLUSION

Urinary PSA could contribute to an early detection of local recurrences of prostate cancer after a radical prostatectomy.

Clinical collection and protein properties of expressed prostatic secretions as a source for biomarkers of prostatic disease

The prostate gland secretes many proteins in a prostatic fluid that combines with seminal vesicle derived fluids to promote sperm activation and function. Proximal fluids of the prostate that can be collected clinically are seminal plasma and expressed-prostatic secretion (EPS) fluids. EPS represents the fluid being secreted by the prostate following a digital rectal prostate massage, which in turn can be collected in voided urine post-exam. This collection is not disruptive to a standard urological exam, and it can be repeatedly collected from men across all prostatic disease states. A direct EPS fluid can also be collected under anesthesia prior to prostatectomy. While multiple genetic assays for prostate cancer detection are being developed for the shed epithelial cell fraction of EPS urines, the remaining fluid that contains many prostate-derived proteins has been minimally characterized. Approaches to optimization and standardization of EPS collection consistent with current urological exam and surgical practices are described, and initial proteomic and glycomic evaluations of the of EPS fluid are summarized for prostate specific antigen and prostatic acid phosphatase. Continued characterization of the prostate specific protein components of EPS urine combined with optimization of clinical collection procedures should facilitate discovery of new biomarkers for prostate cancer.

Natural history of biochemical recurrence after radical prostatectomy: risk assessment for secondary therapy

PURPOSE

A persistently elevated or rising serum level of prostate-specific antigen (PSA) after radical prostatectomy is indicative of recurrent prostate cancer. The natural history of PSA-defined biochemical recurrence (BCR) is highly variable. While a rising PSA level universally antedates metastatic progression and prostate cancer-specific mortality (PCSM), it is not a surrogate for these endpoints. Thus, the management of patients with BCR is controversial.

METHODS

A literature review was conducted to determine the incidence and natural history of BCR, prognostic factors for clinical progression (CP), and the available evidence supporting local or systemic salvage therapy for these patients.

RESULTS

BCR is best defined as two successive PSA levels > or =0.4 ng/ml, as this correlates most accurately with CP. PSA doubling time (PSA-DT) and prostatectomy Gleason score are the variables that best predict the development of distant metastasis and PCSM. Prognostic models based on these and other variables are useful for assessing the need for salvage therapy and the anticipated outcome following local salvage therapy. A treatment algorithm for managing patients with post-prostatectomy BCR was devised.

CONCLUSIONS

Management of patients with BCR after prostatectomy continues to be a complex and challenging issue. Improved methods for risk stratification allow for identification of patients who require treatment. Furthermore, these methods aid in determination of the pattern of disease recurrence, thereby guiding treatment modality. Randomized trials are essential to determine the value of local or systemic salvage therapy strategies in this patient population.

Serum and urinary measurements of prostatic acid phosphatase (PAP) and prostatic specific antigen (PSA) in dogs

Serum and urinary prostatic acid phosphatase (PAP) and prostatic specific antigen (PSA) from 20 dogs were measured. PAP and PSA tests were carried out in authomatized equipment with commercial kits used for humans. Mean PAP serum value was 0.7U/l and urinary 0.1U/l. Mean serum and urinary PSA were 0.005ng/dl and 0.004ng/dl, respectively. In vivo determination of these two biomarkers in dogs is a new form of diagnosis in veterinary medicine and these values should be correlated with the morphological lesion of the prostate gland.

Prostate-specific targeting using PSA promoter-based lentiviral vectors

The prostate-specific antigen (PSA) promoter is known to be highly tissue specific. Although its tissue specificity has been confirmed, its efficiency of gene transcription is significantly lower compared to known nonspecific viral promoters. These lower levels of promoter activity therefore pose a problem when developing an efficacious gene vector for prostate cancer gene therapy. Thus, selecting an appropriate therapeutic gene and vector system to carry the gene driven by the PSA promoter (PSAP) is important. In the studies described here, a human immunodeficiency virus (HIV)-1-based lentiviral vector carrying either the enhanced green fluorescent protein (EGFP) reporter or the diphtheria toxin A (DTA) gene was constructed. The results demonstrate that the PSA promoter in a lentiviral vector drives genes in prostate cells with satisfactory efficacy and specificity. The tissue-specific expression of the DTA protein efficiently eradicates LNCaP prostate cells in culture. We also infected prostate cancer cells and control cells carried by nude mice with the EGFP lentiviral vector. Significant numbers of EGFP-positive LNCaP cells were detected in all the mice bearing these tumors, but no EGFP-positive control cells were detected in any other mouse tissue. The high levels of expression in prostate cells, compared with the low levels of background expression in other cells, show that the PSAP-lentiviral vector could be a potential useful tool for gene therapy of metastatic prostate cancer.

Prostate-specific antigen in female urine: a prospective study involving 217 women

OBJECTIVES

Histomorphologic studies have provided evidence of prostate-specific antigen (PSA)-producing tissue in the female urethra. Some urine samples from women in a small series were positive for PSA, but no systematic investigation of this subject has been done to date.

METHODS

In a prospective study, we analyzed whether PSA occurs in the urine of women and what factors induce detectable PSA levels. The urine samples of 217 women were analyzed (Hybritech-Tandem E-PSA) under standardized conditions. The impact of urine pH and volume was investigated, and the results were correlated with clinical data (age, residual urine, urinary tract infection and prior sexual intercourse within 48 hours).

RESULTS

A positive PSA level greater than the detection limit of 0.1 ng/mL was found in 11% of the analyzed samples; their mean value was 0.29 ng/mL. pH correction did not result in a significant difference. The voiding volume had no influence on the PSA level. Among the cases of detectable PSA, women younger than 50 years of age (n = 14) had a mean PSA of 0.34 ng/mL and those older than 50 years (n = 9) a mean of 0.23 ng/mL. One of 9 women with and 22 of 208 women without residual urine volume had a detectable PSA level, as did 0 of 20 with and 23 of 197 women without urinary tract infection, and 3 of 7 with and 20 of 210 women without prior sexual intercourse within the previous 48 hours. None of the differences were significant.

CONCLUSIONS

A urine PSA level was detected in 11% of all women studied, with PSA values apparently age dependent. Any urine portion is suitable for analysis. No influence was determined for residual urine volume or urinary tract infection. Sexual intercourse may cause detectable PSA values, but the data of this study did not provide sufficient evidence for this hypothesis.

Urine based markers of urological malignancy

PURPOSE

A number of urine based markers have been and are being investigated for the diagnosis and prognostication of urological conditions. A majority of these markers have been evaluated in urological neoplasms, particularly bladder cancer. The diagnosis of bladder cancer currently relies on identifying malignant cells in the urine and subsequently visualizing the tumor on cystoscopy. This diagnosis is further confirmed by transurethral resection or biopsy. While urine cytology is specific, it is not sensitive, especially for detecting low grade disease. This characteristic has prompted the search for more accurate markers of bladder cancer. In this review we critically examine the results of studies evaluating various markers for bladder cancer.

MATERIALS AND METHODS

The published literature on urine based markers for all urological diseases, particularly bladder cancer, was identified using a MEDLINE search and critically analyzed. The sensitivity, specificity, positive and negative predictive values of the various markers were compared. The benefit of using combined markers rather than a single marker was also analyzed from published reports.

RESULTS

Most published literature on urine based markers for urological malignancies involve such markers for diagnosing and prognosticating bladder cancer. Hence, we focused mainly on urine based markers in bladder cancer. Most markers appear to have an advantage over urine cytology in terms of sensitivity, especially for detecting low grade, superficial tumors. However, most markers tend to be less specific than cytology, yielding more false-positive results. This scenario is more common in patients with concurrent bladder inflammation or other benign bladder conditions. However, there is reason to be optimistic about several new markers that appear to provide better specificity. Few urine based markers have been identified and investigated in other urological tumors.

CONCLUSIONS

Detecting bladder cancer using diagnostic markers still presents a challenge. A number of new markers are currently available that appear to be significantly more accurate than cytology. However, further studies involving a larger number of patients are required to determine their accuracy and widespread applicability for diagnosing bladder cancer. Urine based markers do not appear to have a significant role in the diagnosis or prognosis of other urological malignancies, such as prostate, kidney or testicular cancer.

Identification of a superimmunoglobulin gene family member overexpressed in benign prostatic hyperplasia

BACKGROUND

Benign prostate hyperplasia (BPH), a nonmalignant disease with an increasing rate of occurrence associated with advancing age, requires auxiliary markers to help identify its presence and distinguish its progression from prostate cancer.

METHODS

Hybridoma technology was used to generate an antibody against a BPH antigen, which was subsequently characterized by Western blot analysis, sequence homology, and RT-PCR.

RESULTS

A BPH-associated protein, designated P25/26, was identified that showed a strong sequence similarity with superimmunoglobulin family members, overexpressed in BPH, with lower expression observed in both normal and prostate cancer tissues.

CONCLUSIONS

Further studies appear warranted to assess the role that this and other superimmunoglobulin family members may have in the pathogenesis of BPH, and to determine if these glycoproteins have any clinical utility in the differential diagnosis or therapeutic monitoring of BPH.

Human Kallikrein 2 (hK2) and prostate-specific antigen (PSA): two closely related, but distinct, kallikreins in the prostate

Recent studies on human kallikrein 2 (hK2) have revealed striking similarities and significant differences with the closely related kallikrein PSA. Both PSA and hK2 are primarily localized to the prostate and share close structural similarities. Although both kallikreins are produced by the same secretory epithelial cells in the prostate, hK2 is associated more with prostate tumors than PSA and is highly expressed in poorly differentiated cancer cells. The potent trypsin-like activity of hK2 contrasts with the weak chymotrypsin-like activity of PSA. The inactive precursor form of PSA, proPSA, is converted rapidly to active PSA by hK2, suggesting an important in vivo regulatory function by hK2 on PSA activity. The high homology between hK2 and PSA results in significant cross-reactivity to hK2 by polyclonal and some monoclonal antibodies to PSA. Future studies on both PSA and hK2 need to take into account this potential for cross-reactivity. Specific monoclonal antibodies to hK2 have now demonstrated that serum levels of hK2, like PSA, are correlated with prostate cancer. The production of hK2 protein in active protease form and specific monoclonal antibodies to the hK2 antigen will allow extensive future studies delineating the physiological and clinical utility of this new prostate antigen.

Influence of digital rectal massage on urinary prostate-specific antigen: interest for the detection of local recurrence after radical prostatectomy

BACKGROUND

Following radical prostatectomy, urinary prostate-specific antigen (uPSA) may originate from periurethral glands or from recurrent carcinomatous prostatic cells. We evaluated massage of the urethro-vesical anastomosis as a uPSA-releasing method for the detection of local recurrence.

METHODS

PSA was assessed (PSA IMx, Abbott Diagnostic, Rungis, France) in serum and in the first voided urine before and after massage in 59 patients: 7 after cystoprostatectomy for bladder cancer, 22 with prostate in situ, and 30 after radical prostatectomy for prostate cancer.

RESULTS

No significant changes of uPSA were induced by the massage in cystoprostatectomy patients and in 4 radical prostatectomy patients with a negative biopsy of the anastomosis. In contrast, a significant increase of uPSA was observed after massage in the patients with prostate in situ and in 6 radical prostatectomy patients with biopsy-proven local relapse.

CONCLUSIONS

uPSA before and after massage of the prostatic fossa may constitute a new and efficient tool for the detection of local recurrence, if these preliminary results are confirmed on a larger scale.

Molecular forms of prostate-specific antigen and human kallikrein 2 (hK2) in urine are not clinically useful for early detection and staging of prostate cancer

OBJECTIVES

Prostate-specific antigen (PSA), a member of the human kallikrein (hK) family, is the most important tumor marker for early detection, staging, and monitoring of men with prostate cancer today. However, the sensitivity of serum PSA is not sufficient to be used alone for prostate cancer screening. Recently, it was reported that the serum-to-urinary total PSA ratio improves the detection of men with prostate cancer, especially in men with a serum total PSA level between 4.0 and 10.0 ng/mL. We tested this hypothesis by evaluating the clinical usefulness of this PSA ratio as well as the use of the different molecular forms of PSA and human kallikrein 2 (hK2) in urine for detection and staging of prostate cancer.

METHODS

One hundred ten fresh, midstream urine specimens (prostate cancer 62, benign prostatic hyperplasia [BPH] 38, healthy male control 5, women 5) were collected. Serum total PSA, urine total PSA, urinary free PSA, urinary alpha 1-antichymotrypsin-bound PSA, and urinary hK2 levels were determined by monoclonal antibody assays (Hybritech Inc.). The serum-to-urinary total PSA ratio was calculated.

RESULTS

The serum-to-urinary total PSA ratio did not accurately distinguish between men with BPH and men with prostate cancer. There was no significant difference between the urinary levels of any of the molecular forms of PSA or hK2 between men with prostate cancer and men with BPH. Among men with prostate cancer, neither urinary hK2 nor urinary levels of any of the molecular forms of PSA correlated with age, pathologic stage, or Gleason grade.

CONCLUSIONS

In our study, the serum-to-urinary total PSA ratio did not improve the detection of men with prostate cancer. Furthermore, measurement of the molecular forms of PSA and hK2 in urine did not improve the detection or staging of prostate cancer over serum PSA alone.

Urotherapy for patients with cancer

Cancer cells release various antigens, some of which appear in the urine. Oral autourotherapy is suggested as a new treatment modality for cancer patients. It will provide the intestinal lymphatic system with the many tumor antigens against which antibodies may be produced. These antibodies may be pierced through the blood stream and attack the tumor and its cells.

Serum-to-urinary prostate specific antigen ratio: its impact in distinguishing prostate cancer when serum prostate specific antigen level is 4 to 10 ng./ml

PURPOSE

Benign prostatic hyperplasia (BPH) was shown to be associated with high concentrations of urinary prostate specific antigen (PSA). We investigated the serum-to-urinary PSA ratio in patients undergoing prostate biopsy to assess its efficacy in enhancing serum PSA specificity in the detection of prostate carcinoma.

MATERIALS AND METHODS

From November 1995 through January 1996 consecutive patients undergoing prostate biopsy were prospectively included in the study. Serum and urine PSA levels were measured at our laboratory with the Tandem-R assay. Samples were drawn 24 hours before prostate biopsy and at a distance from prostatic manipulation or ejaculation.

RESULTS

We studied 73 patients with BPH and 57 with prostate cancer. Differences between BPH and prostate cancer were statistically significant considering serum PSA or serum-to-urinary PSA ratios. In the 50 patients with a serum PSA of 4.0 to 10.0 ng./ml. (35 with BPH and 15 with prostate cancer) the differences between prostate cancer and BPH were still significant only when considering serum-to-urinary PSA ratio. Receiver operating characteristic curves showed that serum-to-urinary PSA ratio was a better predictor of prostate cancer than serum PSA.

CONCLUSIONS

Our results suggest that the serum-to-urinary PSA ratio may be useful in distinguishing BPH from prostate cancer, particularly in the diagnostic gray zone of serum PSA between 4.0 and 10.0 ng./ml.

Molecular forms of prostate-specific antigen and the human kallikrein gene family: a new era

Without question, much has been learned about the glycoprotein PSA in recent years. By increasing our understanding of this tumor marker's biochemical and physiologic properties, we will be able to improve its clinical utility. The discovery of the various molecular forms of PSA represents a significant advancement. Knowing the concentration and ratio of these PSA forms will be valuable in deciding which patients require further evaluation with transrectal ultrasound and prostate biopsy and which men can be monitored safely without undergoing further invasive testing. This information will be most valuable in treating the patient with a mildly elevated serum PSA level. Although assays are not yet available to detect specifically hK2, the striking similarities of hK2 to PSA, including selective expression in the prostate, suggest that this marker may also prove useful in prostate cancer management. Indeed, a new era of PSA testing has been entered, and the entire field of prostate cancer will benefit.

Rate of relapse following treatment for localized prostate cancer: a critical analysis of retrospective reports

PURPOSE

Controversy exists over the optimal treatment for patients with clinically localized prostate cancer. Almost all of the treatment results are from non-randomized trials and interseries comparison is difficult since the apparent success of a treatment, as judged by the actuarial freedom from relapse and survival data, depends on patient selection criteria and post-treatment evaluation, in addition to the efficacy of the therapeutic intervention. In this report the calculation of a hazard function is used to estimate and compare the rate of relapse for the different treatments.

METHODS AND MATERIALS

Clinical reports from major surgery and radiation oncology treatment institutions were analyzed. The actuarial recurrence data were used to calculate the annual rate of recurrence within each series.

RESULTS

For all but the lowest volume tumors, patients continue to be at risk of relapse for as long as these series have been followed. Despite the heterogeneity of patient populations, the recurrence rates by stage are similar for patients treated with surgery or irradiation. This result is consistent with pathologic data from prostatectomy specimens which indicate that for lesions > 12 cm3 (approx. 3 cm in diameter) there is high likelihood of extraprostatic disease.

CONCLUSION

Treatment outcome for patients with localized prostate cancer may be more dependent on the inherent tumor biology than the particular type of treatment. Accordingly, the expectation and recommendation of a treatment must take into consideration the continued risk of relapse with either radiation therapy or surgery. There are, as yet, insufficient data regarding the impact of screening and earlier diagnosis on the curability of patients with localized prostate cancer.

Urinary prostate specific antigen levels after radical prostatectomy

It was recently demonstrated that urinary prostate specific antigen (PSA) is discordant with serum PSA in many patients after radical prostatectomy. This observation led to the speculation that elevated urinary PSA in the face of undetectable serum PSA may indicate early disease recurrence. We measured urinary PSA levels in 30 patients who had undergone radical prostatectomy for prostate carcinoma and 7 patients who had undergone cystoprostatectomy for bladder cancer. PSA levels of randomly collected urine samples ranged from 0.00 to 22.9 ng./ml. and 0.01 to 8.37 ng./ml., respectively. There was no correlation among urinary and serum PSA levels, pathological stage or type of operation. In 14 patients who had undergone radical prostatectomy and who had measurable levels of urinary PSA voided specimens were divided into initial stream and end stream voided samples. The PSA levels in the end stream voided samples were significantly less than the initial stream sample in 12 of the 14 patients. In men who had undergone radical prostatectomy urethral swab samples were analyzed for PSA. Of 26 patients 24 had detectable levels of urethral swab PSA (range 0.01 to 39.04 ng./ml., median 0.93 ng./ml.). Urethral swab PSA levels did not correlate with serum PSA values or pathological stage of disease. Of 7 patients who had defunctionalized urethras after radical cystoprostatectomy 5 had significantly elevated PSA in the urethral wash or swab samples (range 4.3 to 24.5 ng./ml.). Immunohistochemical analysis of urethrectomy specimens demonstrated positive staining for PSA in 3 of 4 specimens. We conclude that the major source of urinary PSA following total prostatectomy is the urethra itself rather than residual prostate tissue. Measuring serial urinary PSA appears to have limited value in monitoring patients after radical prostatectomy. Whether this urethral PSA can ever contaminate the serum levels of PSA after radical prostatectomy is currently under investigation.

An analysis of urinary prostate specific antigen before and after radical prostatectomy: evidence for secretion of prostate specific antigen by the periurethral glands

We investigated whether urinary prostate specific antigen (PSA) might be a useful marker to detect locally recurrent tumor after radical prostatectomy. We also investigated whether PSA in the first 1 to 5 cc of voided urine is a more useful indicator of urinary PSA levels than the midstream urine PSA, since the first portion of the voided urine contains the highest concentration of prostatic and urethral secretions. To determine the response of urinary PSA to radical prostatectomy, we obtained first voided and midstream urine PSA levels in 18 patients with adenocarcinoma of the prostate before and after surgery. Mean first voided urine PSA levels decreased from 915.1 ng./ml. (range 21 to 2,853) preoperatively to 21.4 ng./ml. (range 0.9 to 88) postoperatively, while mean midstream urine PSA levels decreased from 245.9 ng./ml. (range 5 to 1,312) preoperatively to 1.8 ng./ml. (range 0 to 20.4) postoperatively. We also obtained postoperative first voided and midstream urine PSA levels in 9 prostate cancer patients who had undergone radical prostatectomy, and were considered to be cured by rigid clinical and histological criteria. To distinguish bladder versus urethral sources of urinary PSA in patients without a prostate, we additionally studied 11 patients without prostate cancer who had undergone cystoprostatectomy with orthotopic bladder substitution and who had undetectable serum PSA levels by the ultrasensitive assay. In the cured prostatectomy patients the mean first voided urine PSA level was 40.2 ng./ml. (range 2.8 to 100) and the mean midstream urine PSA level was 3.4 ng./ml. (range 0.1 to 15.2), while in the cystoprostatectomy patients these levels were 15.5 ng./ml. (range 0.8 to 49.9) and 1.2 ng./ml. (range 0 to 6.4), respectively. We conclude that the first voided urine sample better reflects local PSA production by the prostate than the midstream sample, first voided urine PSA decreases significantly in response to radical prostatectomy but is still present in measurable amounts even in surgically cured prostate cancer patients and urethral secretion of low levels of PSA persists after radical prostatectomy. This finding diminishes the chance that the first voided urine PSA level will be a useful marker to detect locally recurrent tumor after radical prostatectomy. Further studies are needed to determine if there is a critical level of first voided urine PSA after radical prostatectomy above which there is an increased likelihood of locally recurrent tumor but overall urinary PSA is highly unlikely to be clinically useful.