The Periurethral Glands do not Significantly Influence the Serum Prostate Specific Antigen Concentration

Prostate-Specific Antigen as a Marker of Hyperandrogenism in Women and Its Implications for Antidoping

BACKGROUND

Since its discovery in the 1970s, prostate-specific antigen (PSA) has become widely known as a biomarker of prostate cancer in males but has often been overlooked in female malignancies. Although the serum concentration of PSA differs between men and women by about 1000-fold, studies have suggested that PSA concentrations drastically differ among healthy females and those who exhibit increased androgen production.

CONTENT

There have been reports of increased PSA expression in women exhibiting hyperandrogenic states, including polycystic ovary syndrome and hirsutism, as well as marked increases in a subset of breast cancer patients. These findings have not only revealed the remarkable diagnostic potential of PSA in a diverse range of clinical conditions but also point to its potential of becoming a useful biomarker of steroid hormone doping among female athletes. Recently, highly sensitive assays that can measure PSA at low limits of detection have been developed, which will aid in the discrimination of PSA between these different conditions.

SUMMARY

The overall aim of this review is to revisit the expression of PSA in hormonally-regulated tissues and in female malignancies, and to demonstrate how the regulation of PSA permits its use in antidoping initiatives.

What are the possible reasons for urethral PSA varieties after radical prostatectomy?

OBJECTIVE

To examine the possible reasons for great varieties in urethral prostate specific antigen (urPSA) levels, in patients after radical prostatectomy (RP).

MATERIALS AND METHODS

In 46 patients with pros-tate cancer, PSA, urPSA, total testosterone, body-mass index (BMI) and the stage of androgenic alopecia (AGA) were determined. Forty-five patients underwent retropubic RP, while one underwent cystoprostatectomy with orthotopic bladder construction, due to bladder cancer.

RESULTS

Average patients age prior to surgery plus or minus standard deviation was 65.2 +/- 5.8 years. Average urPSA was 20.9 +/- 47.5 ng/ml (0.05 to 212 ng/ml, median 2.24 ng/ml). With urethral PSA cut-off of 2.0 ng/ml, two groups were formed: A (urPSA < 2.0 ng/ml) and B (urPSA = 2.0 ng/ml). Patients in the group A had significantly lower average AGA score, than the patients from the group B (2.4 +/- 1.3 vs. 4.4 +/- 2.2, p = 0.0003). In addition, patients from the group A had significantly lower pos-toperative PSA (0.07+0.08 ng/ml vs. 0.14 +/- 0.06 ng/ml, p = 0.0014).

CONCLUSIONS

The patients with higher urPSA have higher AGA scores and higher postoperative PSA. This phenomenon is probably the consequence of higher local dihydrotestosterone activity in the scalp and PSA-secreting urethral glands.

Changes in Serum Prostate-Specific Antigen Levels after Potassium-Titanyl-Phosphate (KTP) Laser Vaporization of the Prostate

Purpose

The prostate-specific antigen (PSA) level decreases after transurethral resection of the prostate (TURP). However, changes in the PSA level after potassium-titanyl-phosphate (KTP) laser vaporization of the prostate are not well known. The aim of this study was to investigate the effect of KTP laser vaporization of the prostate on PSA levels in patients with benign prostatic hyperplasia (BPH).

Materials and Methods

Serum PSA levels were checked before and 1, 3, 6, and 12 months after the procedure in patients who underwent KTP laser vaporization between October 2004 and August 2008. Patients with prostate cancer, a history of urinary retention, or prostatitis during the follow-up period were excluded. The results for 278 patients were studied.

Results

The mean age of the patients was 69.0±6.7 years (range, 50-91 years) and the mean preoperative PSA level was 2.72±2.93 ng/ml. The PSA level tended to be increased at 1 month after the operation (3.18±3.23 ng/ml, p=0.032) but decreased within 3 months and became stabilized after 6 months at 1.79±1.82 ng/ml (p<0.001).

Conclusions

PSA levels may increase after KTP laser vaporization for a certain period of time, but eventually decrease and become stabilized after 6 months. Therefore, it may be appropriate to wait up to 3 months if the PSA level rises after the procedure, and further investigation should be considered if the PSA level still remains high after 6 months.

Urinary PSA level and relative tumor volume after prostate biopsy

OBJECTIVES

To estimate the ratio between urinary prostate specific antigen (uPSA) and tumor volume after prostate biopsy.

METHODS

From 2000 to July 2008, uPSA concentration was determined in 60 patients with clinically organ-confined prostate cancer (PCa). All patients underwent six-area transrectal ultrasound (TRUS)--guided biopsy, with at least 12 biopsy cores. Single pathologist determined tumor grade (G), Gleason score (GS), the percentage of tumor infiltration (% TI) and the percentage of positive cores (% PC) in all biopsy cores. Additionally, relative tumor-biopsy volume (RTV) was calculated by multiplying % PC, % TI and prostate ultrasound-derived volume (Vol). Forty-one patients underwent retropubic radical prostatectomy (RRP), while 19 patients underwent radiation therapy.

RESULTS

Average uPSA was 308.6 +/- 311.9 ng/ml (range 0.06-988 ng/ml), average PSA was 9.7 +/- 5.5 ng/ml (range 1.2-24.3 ng/ml), tumor grade 1.7 +/- 0.8, Gleason score 5.2 +/- 1.3, the percentage of tumor infiltration 27.6 +/- 21.8%, and the percentage of positive cores, 52.2 +/- 30.7%. Average RTV was 6.3 +/- 8.4 ml (0.29-56 ml). All patients were divided in two groups: I, with RTV 4 ml and II, with RTV = 4 ml. The patients with RTV 4 ml had lower G (1.4 +/- 0.6 vs. 2.1 +/- 0.8, p = 0.0002), lower GS (4.5 +/- 1 vs. 5.8 +/- 1.3, p = 0.003) and higher uPSA (389.4 +/- 340.8 vs. 193.1 +/- 229.7, p = 0.014). There were no differences in serum PSA levels between the groups.

CONCLUSION

Relative tumor-biopsy volume (RTV) is useful parameter in the preoperative assessment of tumor volume. Patients with higher RTV had significantly higher G and GS. However, these patients had significantly lower uPSA. This phenomenon could be the consequence of compromised PSA drainage from the peripheral zone of the prostate, caused by the tumor.

Nanoparticle-based bio-barcode assay redefines "undetectable" PSA and biochemical recurrence after radical prostatectomy

We report the development of a previously undescribed gold nanoparticle bio-barcode assay probe for the detection of prostate specific antigen (PSA) at 330 fg/mL, automation of the assay, and the results of a clinical pilot study designed to assess the ability of the assay to detect PSA in the serum of 18 men who have undergone radical prostatectomy for prostate cancer. Due to a lack of sensitivity, available PSA immunoassays are often not capable of detecting PSA in the serum of men after radical prostatectomy. This new bio-barcode PSA assay is approximately 300 times more sensitive than commercial immunoassays. Significantly, with the barcode assay, every patient in this cohort had a measurable serum PSA level after radical prostatectomy. Patients were separated into categories based on PSA levels as a function of time. One group of patients showed low levels of PSA with no significant increase with time and did not recur. Others showed, at some point postprostatectomy, rising PSA levels. The majority recurred. Therefore, this new ultrasensitive assay points to significant possible outcomes: (i) The ability to tell patients, who have undetectable PSA levels with conventional assays, but detectable and nonrising levels with the barcode assay, that their cancer will not recur. (ii) The ability to assign recurrence earlier because of the ability to measure increasing levels of PSA before conventional tools can make such assignments. (iii) The ability to use PSA levels that are not detectable with conventional assays to follow the response of patients to adjuvant or salvage therapies.

Usefulness of the nadir value of serum prostate-specific antigen measured by an ultrasensitive assay as a predictor of biochemical recurrence after radical prostatectomy for clinically localized prostate cancer

INTRODUCTION

The objective of this study was to determine whether the nadir value of serum prostate-specific antigen (PSA) measured by an ultrasensitive assay could be a useful predictor of biochemical recurrence after radical prostatectomy for clinically localized prostate cancer.

MATERIALS AND METHODS

This study included 127 patients who underwent radical prostatectomy for clinically localized prostate cancer without neoadjuvant hormonal therapy and were pathologically diagnosed as negative for lymph node metastasis. The serum PSA value was measured using an ultrasensitive PSA assay system (Roche Diagnostics, Mannheim, Germany), and the findings were analyzed with respect to several clinicopathological factors. In this series, biochemical recurrence was defined as PSA persistently >0.2 ng/ml.

RESULTS

Based on the nadir PSA value, we divided 127 patients into three groups as follows: group A (n=99):<or=0.01 ng/ml; group B (n=16): 0.01-0.05 ng/ml, and group C (n=12): >or=0.05 ng/ml. The nadir PSA value was significantly associated with preoperative PSA value, but not other conventional clinicopathological prognostic parameters. During the observation period (median 31 months, range 6-75 months), biochemical recurrence occurred in 16 patients, that is, 1 in group A (6.3%), 4 in group B (25.0%), and 11 in group C (91.7%). Multivariate analysis using the Cox proportional hazards regression model indicated that the nadir PSA value was an independent predictor for biochemical recurrence after radical prostatectomy.

CONCLUSION

These findings suggest that the nadir serum PSA value measured by an ultrasensitive assay could be a useful predictor of biochemical recurrence after radical prostatectomy for clinically localized prostate cancer, and that careful follow-up should be considered in cases demonstrating a nadir PSA value>0.01 ng/ml because of the significantly higher probability of biochemical recurrence in such cases.

Expression of prostate-specific antigen (PSA) and human glandular kallikrein 2 (hK2) in ileum and other extraprostatic tissues

Prostate-specific antigen (PSA) is a widely used marker for prostate cancer. In the literature, there are reports of nonprostatic expression of PSA that potentially can affect early diagnosis. However, the results are scattered and inconclusive, which motivated us to conduct a more comprehensive study of the tissue distribution of PSA and the closely related protein human glandular kallikrein 2 (hK2). RT-PCR, in situ hybridization and immunohistochemistry were used to detect expression of both PSA and hK2 in secretory epithelial cells of trachea, thyroid gland, mammary gland, salivary gland, jejunum, ileum, epididymis, seminal vesicle and urethra, as well as in Leydig cells, pancreatic exocrine glands and epidermis. Immunometric measurements revealed that the concentration of PSA in nonprostatic tissues represents less than 1% of the amount in normal prostate. Pronounced expression of PSA was detected in the Paneth cells in ileum, which prompted us to compare functional parameters of PSA in ileum and prostate. We found that in homogenates from these 2 tissues, PSA manifested equivalent amidolytic activity and capacity to form complexes with protease inhibitors in blood in vitro. Thus, PSA released from sources other than the prostate may add to the plasma pool of this protein, but given the lower levels detected from those sites, it is unlikely that nonprostatic PSA normally can interfere with the diagnosis of prostate cancer. Nevertheless, this risk should not be neglected as it may be of clinical significance under certain circumstances. Supplementary material for this article can be found on the International Journal of Cancer website at http://www.interscience.wiley.com/jpages/0020-7136/suppmat/index.html.

Biochemical recurrence without PSA progression characterizes a subset of patients after radical prostatectomy. Prostate-specific antigen

OBJECTIVES

To characterize a subset of patients with biochemical recurrence after radical prostatectomy but with little, if any, subsequent rise in serum prostate-specific antigen (PSA) and no clinical progression during long-term follow-up.

METHODS

Of a series of 600 patients, 158 with biochemical recurrence after radical prostatectomy were examined. We identified a subset with measurable serum PSA levels during long-term follow-up, but with very low PSA velocity and no clinical recurrence. Serum PSA was measured with the ultrasensitive TOSOH assay with a PSA recurrence defined as a serum PSA of 0.07 ng/mL or greater.

RESULTS

We identified 14 patients (8.8% of biochemical recurrences) with a detectable serum PSA level after radical prostatectomy yet without clinical or PSA progression at a mean follow-up after radical prostatectomy of 10.3 years. The mean time to PSA recurrence was 5.8 years, and the mean PSA velocity after recurrence was 0.028 ng/mL/yr. No clinical or pathologic features were found that could be used to identify this subset of patients.

CONCLUSIONS

A subset of patients with biochemical recurrence after radical prostatectomy will not exhibit a progressive rise in serum PSA or clinical progression at 10 years follow-up. This suggests that serum PSA kinetics should be observed after biochemical recurrence before adjuvant hormonal therapy or radiotherapy.

Serum and Urinary Prostate-specific Antigen and Urinary Human Glandular Kallikrein Concentrations Are Significantly Increased after Testosterone Administration in Female-to-Male Transsexuals

Background: The genes that encode prostate-specific antigen (PSA) and human glandular kallikrein (hK2) are up-regulated by androgens and progestins in cultured cells, but no published studies have described the effect of androgen administration in women on serum and urinary PSA or hK2.

Methods: We measured serum and urinary PSA and hK2 before, and 4 and 12 months post testosterone treatment by immunofluorometric methods in 32 female-to-male transsexuals.

Results: Mean serum PSA increased from 1.1 ng/L to 11.1 ng/L and then to 22 ng/L by 4 and 12 months post treatment, respectively; the corresponding mean values in urine were 17, 1420, and 18 130 ng/L, respectively. Serum hK2, another kallikrein closely related to PSA, remained undetectable at the three time points. However, urinary hK2 concentration rose from below the detection limit (&lt;6 ng/L) before treatment to 18 and 179 ng/L by the 4th and the 12th month of treatment, respectively. All changes were statistically significant (P &lt;0.001) at 4 months.

Conclusions: Testosterone administration increases serum and urinary PSA and urinary hK2 in women. These measurements may be useful as indicators of androgenic stimulation in women.

Prostate-specific antigen in acute hepatitis and hepatocellular carcinoma

BACKGROUND

Prostate-specific antigen (PSA) is the most important tumor marker in prostate cancer diagnosis and follow-up. Its catabolism by the liver has not influenced its use as a prostate marker until the recent report of a significant increase in a man and a woman with acute hepatitis. In addition, PSA was detected in liver tumor extracts, which warranted its evaluation in liver cytolysis and hepatocellular carcinoma. In this study, PSA was evaluated in a cohort of both sexes presenting either acute hepatitis or hepatocellular carcinoima.

METHODS

Forty-two patients with acute hepatitis (21 male patients, 21 female patients) and 54 patients with hepatocellular carcinoma (31 male patients, 23 female patients) were tested for PSA by equimolar immunoassay (Abbott AxSYM Total PSA, Abbott Diagnostics, Rungis, France) and for relevant liver biological parameters (alpha-fetoprotein, alanine aminotransferase, aspartate aminotransferase, total bilirubin, and prothrombin rate).

RESULTS

PSA was undetectable in all the female patients and was consistent with age in the males (PSA median and range in acute hepatitis, 0.36 microg/l (range, 0.05-1.3); in hepatocellular carcinoma, 0.36 microg/l (range, 0.02-3.9)). It did not correlate with alpha-fetoprotein and aminotransferases.

CONCLUSIONS

Our results confirm the well-established reliability of PSA, and show that PSA remains a valid prostate marker in patients with acute hepatitis and hepatocellular carcinoma.

Effect of neoadjuvant hormonal therapy on prostatic intraepithelial neoplasia and its prognostic significance

PURPOSE

We studied the effect of neoadjuvant hormonal therapy on prostatic intraepithelial neoplasia in patients undergoing radical prostatectomy and assessed the effect of prostatic intraepithelial neoplasia on disease recurrence as measured by serum prostate specific antigen (PSA).

MATERIALS AND METHODS

A total of 278 patients with clinically localized prostate cancer were included in phase II and III studies evaluating radical prostatectomy alone versus radical prostatectomy following neoadjuvant hormonal therapy at Memorial Sloan-Kettering Cancer Center between October 1991 and August 1996. Patient data related to prostatic intraepithelial neoplasia were analyzed.

RESULTS

Of 275 evaluable patients 145 (52.7%) had prostatic intraepithelial neoplasia. Of 50 patients treated with neoadjuvant hormonal therapy (hormone group) 22 (44%) had a lower incidence of prostatic intraepithelial neoplasia compared to 69 of 80 controls (86.3%) (chi-square test p<0.0001). Of 262 patients (95.3%) with followup PSA 44 (16.8%) had PSA recurrence at a median followup of 32 months, with a median time to recurrence of 30 months. PSA recurrence was noted in 23 of 145 patients with compared to 21 of 130 without prostatic intraepithelial neoplasia (chi-square test p = 0.95), and did not significantly differ between the hormone group (25 of 142, 17.6%) and controls (19 of 130, 14.6%) (chi-square test p = 0.45).

CONCLUSIONS

While patients treated with neoadjuvant hormonal therapy had significantly lower incidence of prostatic intraepithelial neoplasia, neither prostatic intraepithelial neoplasia nor neoadjuvant hormonal therapy significantly affected PSA recurrence at a median followup of 32 months.

Prostate-specific antigen

Prostate specific antigen (PSA) is serine protease produced at high concentrations by normal and malignant prostatic epithelium. It is mainly secreted into seminal fluid, where it digests the gel forming after ejaculation. Only minor amounts of PSA leak out into circulation from the normal prostate, but the release of PSA is increased in prostatic disease. Thus PSA is a sensitive serum marker for prostate cancer but its specificity is limited by a high frequency of falsely elevated values in men with benign prostatic hyperplasia (BPH). Approximately two-thirds of all elevated values (>4 microg/l) in men over 50 years of age are due to BPH. In serum, most of the PSA immunoreactivity consists of a complex between PSA and alpha1-antichymotrypsin (PSA-ACT) whereas approximately 5-40% are free. The proportion of PSA-ACT is larger and the free fraction is smaller in prostate cancer than in benign prostatic hyperplasia (BPH). Determination of the proportion of free PSA has become widely used to improve the cancer specificity of PSA especially in men with PSA values in the 'grey zone' (4-10 microg/l). PSA also occurs in complexes with other protease inhibitors and determination of these and other markers may further improve the diagnostic accuracy for prostate cancer. Interpretation of the results for many different markers is complicated, but this can be simplified by using statistical methods. The diagnostic accuracy can be further improved by using logistic regression or neural networks to estimate the combined impact of marker results and other findings like digital rectal examination (DRE), transrectal ultrasound (TRUS) and heredity.

Free-to-total prostate-specific antigen ratios 18-24 months following external beam radiation for adenocarcinoma of the prostate

BACKGROUND AND OBJECTIVES

The purpose of this study was to evaluate free-to-total prostate-specific antigen (PSA) ratios after definitive external beam radiation therapy for men with adenocarcinoma of the prostate (CaP).

METHODS

A prospective evaluation of percent free PSA in men following definitive external beam radiation therapy for CaP was compared to men with untreated CaP and men at very low risk for CaP. Statistical comparison of clinical and pathologic parameters was performed.

RESULTS

There was no statistically significant difference in free-to-total PSA ratios for men with newly diagnosed CaP and men with detectable PSA who were treated with external beam radiation therapy.

CONCLUSIONS

Free-to-total PSA ratios after definitive external beam radiation therapy for CaP are consistent with percent free PSA in patients with newly diagnosed CaP. This supports the theory that PSA from in situ prostate tissue following external beam radiation therapy is produced by malignant cells.

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.

Relation of free PSA/total PSA in serum for differentiating between patients with prostatic cancer and benign hyperplasia of the prostate: which cutoff should be used?

A review on literature data is given concerning free prostate-specific antigen (f-PSA) and the corresponding cutoffs of f-PSA/t-PSA for differentiating patients with cancer of the prostate from those with benign prostatic hyperplasia. The special importance of the diagnostic criterion (sensitivity, specificity, efficiency) for establishing the cutoff is demonstrated. On the basis of our own data, the application of the f-PSA% is recommended as an additional decision criterion for biopsy.

Early detection of recurrent prostate cancer with an ultrasensitive chemiluminescent prostate-specific antigen assay

OBJECTIVES

Treatment failure after radical prostatectomy is most commonly heralded by an increase in serum prostate-specific antigen (PSA) to detectable levels. We evaluated the clinical utility of an ultrasensitive chemiluminescent PSA assay.

METHODS

We evaluated the assay in banked sera obtained from 170 men after radical prostatectomy. Controls consisted of 142 females, 29 men who had undergone cystoprostatectomy without evidence of prostate cancer, and 25 men without evidence of recurrent disease at least 5 years after prostatectomy for organ-confined disease. Lead time to diagnosis of recurrence was based on comparisons with the IMx or Tandem E assays using a cutoff of 0.1 ng/mL (100 pg/mL).

RESULTS

The biologic level of detection of this assay is 8 pg/mL. Serum PSA levels were undetectable in 82.4% of females, 86.2% of the cystoprostatectomy patients, and 96% of the radical prostatectomy controls. After radical prostatectomy, PSA levels were undetectable at last check in 104 of 168 (61.9%) men. In the 24 men with prostate cancer recurrence, the enhanced sensitivity of 8 pg/mL provided a mean lead time based on conservative calculations of 12.7 to 22.5 months over conventional assays. Thirty-four of the 41 men with detectable PSA levels and no evidence of disease recurrence had PSA levels of 30 pg/mL or less.

CONCLUSIONS

PSA levels are undetectable in most men who do not have recurrence of disease after radical prostatectomy. Low but detectable serum PSA levels less than or equal to 30 pg/mL can be produced by nonmalignant sources of PSA. PSA assays with enhanced sensitivity can detect recurrent prostate cancer with significant lead time over conventional assays.

The PSA nadir that indicates potential cure after radiotherapy for prostate cancer

OBJECTIVES

The prostate-specific antigen nadir that indicates potential cure by radiotherapy has never been established. We determined this nadir level and used it to define precisely disease freedom after radiotherapy.

METHODS

Combination radioactive 125I prostate implant followed by external-beam radiation was administered to 660 men with clinical Stage T1T2N0 prostate cancer. The average pretreatment prostate-specific antigen level (Tandem R Assay) was 11.7 ng/mL (median 8.0 ng/mL, range 0.3 to 188 ng/mL). To analyze these data, recurrence was defined as a prostate-specific antigen level rising above whatever nadir was achieved. The median follow-up is 42 months (range 12 to 150 months).

RESULTS

Eighty-one percent of all men are calculated to achieve a prostate-specific antigen nadir of 0.5 ng/mL or less and to have a 5- and 10-year disease-free survival rate of 93% and 83%, respectively, as compared with a 5-year disease-free survival rate of 26% for those achieving a nadir of 0.6 to 1.0 ng/mL--a significant difference (P = 0.0001). All men with a nadir greater than 1.0 ng/mL ultimately failed treatment. Of 201 men with a minimum 5-year follow-up, 143 are disease-free and 140 (98%) achieved and maintained a nadir of 0.5 ng/mL or less.

CONCLUSIONS

For possible cure of prostate cancer with radiotherapy, a prostate-specific antigen nadir of 0.5 ng/mL or less should be achieved. With this nadir level, disease freedom after irradiation is defined as achievement and maintenance of a nadir of 0.5 ng/mL or less. A nadir greater than 0.5 ng/mL or subsequent increase above 0.5 ng/mL is defined as irradiation treatment failure. This definition may help resolve the controversy about the potential for cure of prostate cancer by irradiation.

Clinical utility of measurements of free and total prostate-specific antigen (PSA): a review

BACKGROUND

Prostate-specific antigen (PSA) is a widely-used tumor marker to aid in the early detection of prostate cancer. PSA testing has appreciable false-positive and false-negative results, particularly in the 2.5-10.0 ng/ml range. Measurements of the percentage of nonprotein-bound (free) PSA in serum, which is lower in patients with prostate cancer, has been evaluated as a method for increasing the accuracy of PSA testing.

METHODS

The literature on forms of PSA in serum, as it relates to issues of clinical utility for prostate cancer screening, was reviewed and summarized through May 1996.

RESULTS

Measurements of the percentage of free PSA in serum increase the accuracy of PSA testing for prostate cancer in men whose total PSA levels are 2.5-10.0 ng/ml. Cutoffs for screening are affected by prostate volume and total PSA levels. One study also demonstrated a correlation between percentage of free PSA and pathologic features of cancer aggressiveness.

CONCLUSIONS

Measurement of free PSA in serum has potential clinical utility for increasing the sensitivity and specificity of PSA screening. Insufficient data are available to establish cutoffs to be used in clinical practice. Cutoffs are affected by total PSA level and prostate volume. The prevalence rate of cancer in the screened population (age, race, previous biopsy history, etc.) will also influence screening cutoffs. Percentage of free PSA may also correlate with the potential aggressiveness of early-stage prostate cancer.