A comparison of six commercial assays for total and free prostate specific antigen (PSA): the predictive value of the ratio of free to total PSA

OBJECTIVE: To evaluate the clinical utility of six commercial assays for free prostate specific antigen (fPSA) and the derived ratio of fPSA to total PSA in distinguishing between patients with prostate cancer or benign prostate hyperplasia (BPH). MATERIALS AND METHODS: Each assay was evaluated against a panel of serum samples comprising those from patients with prostatic disease, other malignancies, normal subjects and sera containing substances which might interfere with the immunoassay. RESULTS: The levels of total (tPSA), fPSA and their ratio (f/tPSA) were compared among the different samples. All assays showed similar specificities for prostate carcinoma but differed in the positive predictive values of f/tPSA. CONCLUSIONS: Although all six assays were equimolar, there were differences in calibration, particularly for fPSA. The ability of f/tPSA to discriminate between benign and malignant prostatic disease depended on the assay used. The f/tPSA is not valid when the tPSA and fPSA assays are obtained from different manufacturers.     

Value of prostate specific antigen α1-antichymotrypsin complex for the detection of prostate cancer in patients with a PSA level of 4.1–10.0ng/mL: Comparison with PSA-related parameters

BACKGROUND: The aim of the present study was to evaluate the usefulness of prostate specific antigen alpha1-antichymotrypsin complex (PSA-ACT) in the differential diagnosis of prostate cancer in patients with a PSA level of 4.1-10.0 ng/mL compared to several PSA- and PSA-ACT-related parameters. METHODS: Serum samples were obtained from 103 patients with no evidence of malignancy on biopsy and 29 with histologically confirmed prostate cancer. All patients had pretreatment serum PSA levels between 4.0 and 10.0 ng/mL. The different forms of serum PSA, including total PSA (tPSA), free PSA (fPSA) and PSA-ACT were measured using immunofluorometric techniques with different monoclonal antibodies against PSA and ACT. Furthermore, tPSA and PSA-ACT densities of the whole prostate (PSAD and ACTD, respectively) and the f-to-tPSA and the f-to-PSA-ACT ratios (F/T ratio and F/ACT ratio, respectively) were calculated. RESULTS: The differences between patients with prostate cancer and benign prostatic disease were significant with respect to all six parameters examined in this study. Analysis of receiver operating characteristics revealed that the areas under the curve for PSA-ACT, ACTD and the F/ACT ratio were larger than those for tPSA, PSAD and the F/T ratio, respectively. However, there were no significant differences in discrimination between benign and malignant diseases among these six parameters. CONCLUSIONS: In patients who have an intermediate serum PSA level, PSA-ACT and its associated parameters may not be significantly superior in the differential diagnosis between prostate cancer and benign prostatic diseases compared to tPSA and its traditional relatives.     

Free prostate-specific antigen 'in the field': a useful adjunct to standard clinical practice.

OBJECTIVES: To determine the clinical utility of the ratio of free to total prostate-specific antigen (f/tPSA), which may improve the discrimination of PSA testing in the assessment of patients with prostatic disease, in a busy clinical practice. PATIENTS AND METHODS: A series of 198 men undergoing transrectal ultrasonography (TRUS)-guided biopsy, because of a high total PSA level or an abnormal digital rectal examination or both, had blood samples taken for the assessment of both free and total PSA before any form of prostatic manipulation. The histological findings were compared with tPSA, fPSA and f/tPSA, evaluating three different thresholds of f/tPSA. RESULTS: PSA levels, PSA density and fPSA density differed significantly between those with benign histology and neoplasia. The f/tPSA only differed significantly in men with a PSA level of 10. 1-15 ng/mL. The f/tPSA threshold of 0.25 was the most useful clinically, with a negative predictive value for prostate cancer of 91%. Using this threshold would reduce the negative biopsy rate by 30%. CONCLUSION: The f/tPSA is of clinical value in reducing the negative biopsy rate and in the management of patients with a high PSA level and previous negative biopsies.     

单中心前列腺穿刺活检结果查询表的建立

目的：综合利用PSA及其相关参数建立能够简便查询的前列腺穿刺阳性率查询表.方法纳入2009年7月至2015年3月在解放军总医院行前列腺穿刺活检的患者,收集前列腺体积、游离PSA(free PSA,fPSA)和总PSA(total PSA,tPSA)等临床资料.多因素Logistic回归分析预测前列腺癌的独立性影响因素,并利用相关因素建立前列腺穿刺阳性结果查询表.结果资料完整且病理结果为前列腺癌和前列腺增生的患者纳入研究,共1077例.根据PSA水平分为0~2.5、2.6~4.0、4.1~10.0、10.1~20.0和＞20.0 ng/ml 5组,前列腺癌检出率分别为20.9％、20.0％、37.3％、48.1％和80.2％,随着PSA水平的升高,前列腺癌检出率也明显升高.多因素Logistic回归分析发现tPSA、fPSA和前列腺体积均为前列腺癌的独立性预测因素,tPSA、fPSA百分比(free to total PSA,f/tPSA)和PSA密度(PSA density,PSAD)在前列腺癌和前列腺增生两组间存在显著差异(P＜0.05),综合利用上述3个指标建立前列腺阳性穿刺查询表.结论本研究根据 tPSA、f/tPSA和PSAD建立的查询表为临床前列腺穿刺活检提供了一个简便实用的阳性率查询工具.     

Hormonal predictors of prostate cancer

INTRODUCTION: Androgens are necessary for the development and functioning of the prostate gland. The association of serum testosterone and pituitary hormone levels with prostate cancer development is not completely understood. In this clinical study, we evaluated the role of serum testosterone, free testosterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels in predicting prostate cancer risk in patients who had transrectal ultrasonography-guided prostate biopsy with the suspicion of prostate cancer. MATERIAL AND METHODS: A total of 211 patients who were selected to undergo prostatic biopsy due to abnormal digital rectal examination and/or a serum prostate-specific antigen (PSA) level >2.5 ng/ml were included in the study. The patient characteristics of total PSA, free/total PSA ratio, serum total testosterone, free testosterone, free/total testosterone ratio, FSH and LH levels were compared according to the pathological diagnosis. RESULTS: The mean age was 63.91 years (range 44-83) and the mean PSA level was 9.23 ng/ml (range 0.13-50.41) in the whole group. Of 211 patients, 69 (32.7%) were positive for prostate cancer. The patients who were positive for prostate cancer had statistically lower levels of serum total testosterone compared with the patients who were diagnosed as having benign prostatic hyperplasia (BPH; 405 vs. 450.5 ng/dl, respectively; p = 0.013). The serum FSH level was significantly higher in men with prostatic cancer than in men with BPH (7.56 vs. 6.06 mIU/ml, respectively; p = 0.029). No significant differences between men with prostatic cancer and those with BPH were found for serum LH levels. When normal ranges for serum free and total testosterone levels were defined as 9 pg/ml and 300 ng/dl, respectively, patients who had low free testosterone and total testosterone levels had significantly higher cancer detection rates than patients with high serum androgen levels: 40.8% (40/98) versus 25.6% (29/113) (p = 0.021), and 48.6% (18/37) versus 29.3% (51/174), respectively (p = 0.023). After logistic regression analysis, none of the hormones showed a significant difference in predicting the risk of prostate cancer in patients undergoing prostate biopsy with suspicion of the disease. CONCLUSION: Our data suggest that patients diagnosed with prostate cancer have low levels of serum testosterone and high levels of serum FSH compared with the patients with BPH. No support was found for the theory that high levels of testosterone increase prostate cancer risk. Further studies are needed to clarify the relationship between hormones and prostate cancer etiology.     

Changes in serum levels of prostatic acid phosphatase and prostate specific antigen after luteinizing hormone-releasing hormone analogue administration in patients with metastatic prostatic cancer in relation to glandular differentiation

Eighteen previously untreated patients with metastatic carcinoma of the prostate were treated with LHRH analogue. They were divided into 3 groups according to the degree of glandular differentiation. In all groups, a transient rise of PAP and PSA was observed after the LH and testosterone surge. However, relative values of LH, testosterone, PAP and PSA did not differ significantly among the 3 groups. These facts suggest that a transient rise of PAP and PSA is caused by testosterone surge independently from the degree of glandular differentiation after LHRH analogue administration in patients with advanced prostatic cancer.     

Comparisons of the various combinations of free, complexed, and total prostate-specific antigen for the detection of prostate cancer

OBJECTIVES: We compared the ability of three prostate-specific antigen (PSA) ratios - free-to- total PSA ratio (fPSA/tPSA), free-to-complexed PSA ratio (fPSA/cPSA), and complexed-to-total PSA ratio (cPSA/tPSA) - to distinguish prostate cancer from benign prostatic hyperplasia (BPH). METHODS: We tested 258 consecutive patients who underwent transrectal ultrasound-guided prostate needle biopsy because of an abnormal digital rectal examination or a Tandem-R PSA of >4.1 ng/ml. Free PSA (fPSA) and total PSA (tPSA) were measured by Tandem-R assay. alpha(1)-Antichymotrypsin-complexed PSA (cPSA) was measured by Markit-M PSA-ACT assay. RESULTS: Of the 258 patients, 204 had BPH, and 54 had prostate cancer. The specificity at 96% sensitivity for fPSA/tPSA, fPSA/cPSA, and cPSA/tPSA was 23, 25, and 33%, respectively. Of 162 patients with tPSA between 4.1 and 10.0 ng/ml, 132 had BPH and 30 had prostate cancer. The specificity at 96% sensitivity for f/tPSA, f/cPSA and c/tPSA was 32, 44, and 41%, respectively. There was no significant difference in the area under the receiver-operating characteristic curves among fPSA/tPSA, fPSA/cPSA, and cPSA/tPSA in the overall PSA range or in tPSA between 4.1 and 10.0 ng/ml. CONCLUSION: fPSA/tPSA, fPSA/cPSA, and cPSA/tPSA did not differ in their ability to distinguish prostate cancer from BPH.     

The significance of the free-to-complexed prostate-specific antigen (PSA) ratio in prostate cancer detection in patients with a PSA level of 4.1-10.0 ng/mL

OBJECTIVE: To compare the ratio of free prostate specific antigen (fPSA), total PSA (tPSA) and complexed PSA (cPSA, measured using a novel immunoassay) with other variables used to detect prostate cancer in patients with intermediate serum PSA levels of 4.1-10.0 ng/mL. PATIENTS AND METHODS: From July 1997 to August 1998, 140 consecutive patients were assessed; all had intermediate serum PSA levels and/or abnormal findings on a digital rectal examination. All patients underwent transrectal ultrasonography (TRUS)-guided biopsy, and the prostate and transition zone volumes were determined by TRUS. Free and tPSA were measured using the Tandem-R assay (Hybritech Corp., San Diego, CA). PSA complexed with alpha1-antichymotrypsin (cPSA) was measured using an appropriate assay. The ability of cPSA, free-to-total PSA ratio (f/tPSA), free-to-complexed PSA ratio (f/cPSA), tPSA density of the whole prostate (PSAD), of the transition zone (tPSATZ), and cPSA density of the whole prostate (cPSAD) and of the transition zone (cPSATZ) to improve the power of PSA in detecting prostate cancer was evaluated using receiver operating characteristic (ROC) curves. Results Of the 140 patients, 126 had histologically confirmed benign disease and 14 had prostate cancer. The cPSA alone had better specificity for detecting prostate cancer than had tPSA alone but the difference was not significant. The area under the ROC curve for f/cPSA was larger than those for all other variables. With a 93% sensitivity for detecting prostate cancer, a f/cPSA threshold of 25% would result in fewer unnecessary biopsies (40% f/cPSA specificity) than with all other PSA variables. The difference in the resolution was significant between f/cPSA and tPSA, cPSA, tPSAD and tPSATZ, but not with f/tPSA, cPSAD or cPSATZ. In patients with a prostate volume of < 30 mL, the cPSATZ showed better specificity for prostate cancer than tPSA alone. CONCLUSION: Measuring the level of cPSA and its derivatives may provide better differentiation of prostate cancer and benign disease than tPSA alone in patients with a tPSA level of 4.1-10.0 ng/mL.     

Increased discrimination between benign prostatic hyperplasia and prostate cancer with equimolar total prostate specific antigen measurement

Although prostate specific antigen (PSA) is widely used in the discrimination of benign prostatic hyperplasia (BPH) and prostate cancer, its diagnostic value is controversial due to an appreciable false positive rate. In the present study, we compared a recently introduced assay method, equimolar PSA measurement, to non-equimolar PSA measurement and also determined the diagnostic value of percent free PSA with changing total PSA (tPSA) measurements. Between April 1999 and December 2001, the sera of 61 patients with BPH and 41 with prostate cancer were examined. Total PSA and free PSA was determined using the Immulite 2000 assay system, whereas equimolar tPSA measurement was performed using Bayer PSA Q for the Chiron ACS 180 system. Comparative analysis of the two different assays revealed better diagnostic sensitivity and specificity values for equimolar tPSA measurement, which in turn would have led to 10% of the patients avoiding an unnecessary biopsy. Additionally, percent free PSA with the changing denominator of tPSA assays showed that the free PSA/equimolar tPSA ratio was the best tumor marker among the studied forms of PSA. It was concluded that equimolar tPSA measurement using recombinant Fab fragments is superior to the classical measurements with monoclonal antibodies, and that the use of percent free PSA with the equimolarly measured tPSA has better sensitivity and specificity in the discrimination of benign and malignant diseases of the prostate.     

Longitudinal PSA changes in men with and without prostate cancer: assessment of prostate cancer risk

BACKGROUND: To determine longitudinal PSA changes over a period of 10 years in patients with and without prostate cancer. METHODS: Serial PSA measurements performed over 10 years were evaluated in 353 men who eventually developed prostate cancer and in 2.462 participants of a screening program without prostatic malignancy. RESULTS: In men with cancer, mean tPSA increased from 2.28 ng/ml at 10 years before diagnosis to 6.37 ng/ml at the time of postive biopsy (PSA velocity: 0.409 ng/ml/year). PSA velocity was significantly associated with Gleason scores and pathologic stage. In the benign group (n=2.462), mean tPSA increased from 1.18 to 1.49 ng/ml over a period of 10 years (PSA velocity of 0.03 ng/ml/year). Of the subjects with tPSA levels of 2 ng/ml or less, 2 years prior to cancer diagnosis, 11.4% had tPSA values of more than 4 ng/ml at the time of biopsy. Of the 972 men with tPSA below 1 ng/ml 2 years before the most recent measurement was obtained, 966 (99.4%) had no evidence of prostate cancer 2 years later, while six were found to have malignancies (0.6%). CONCLUSIONS: Longitudinal PSA changes in men with and without prostate cancer are significantly different. Annual testing may not be required in men with baseline tPSA levels of 1 ng/ml or below, whereas in patients with levels higher than 1 ng/ml, it seems to be indicated because of the significant percentage of men presenting with tPSA levels of more than 4 ng/ml two years later.     

PSA相关标志物在前列腺癌诊断中的价值

目的 探讨在前列腺特异抗原(prostate specific antigen,PSA)灰区(PSA 4～10ng/mL)患者中,血清总PSA及游离PSA比值(f/tPSA)、前列腺特异性抗原密度(PSAD)和(f/t) PSA/PSAD值对穿刺病理结果的诊断价值.方法 回顾2008年1月至2016年3月本院接受经直肠超声(transrectal ultrasound,TRUS)引导下前列腺穿刺的患者929例,对其中249例PSA 4～ 10 ng/mL患者的临床资料进行了整理分析.根据病理结果,分为前列腺癌组(PCa组)38例(15.26％),前列腺增生组(BPH组)211例(84.74％).对患者年龄、tPSA、f/tPSA、体积、PSAD、(f/t) PSA/PSAD值进行统计学分析.结果 两组患者的年龄水平比较差异无统计学意义(P＞0.05);在f/tPSA、体积、(f/t) PSA/PSAD水平,BPH组大于PCa组;在tPSA、PSAD水平,PCa组大于BPH组,差异均有统计学意义(P＜0.05).PCa组患者中f/tPSA或PSAD异常者32例,占84.21％:BPH组中f/tPSA或PSAD异常者110例,占52.13％,差异有统计学意义(X2=13.52,P ＜0.005).结论 f/tPSA和PSAD异常对PSA灰区的患者是否行前列腺穿刺具有指导意义.如果f/tPSA和PSAD结果相矛盾,f/tPSA联合PSAD、PSAD联合(f/t) PSA/PSAD的诊断价值相对较高.     

Free/total PSA ratio improves differentiation of benign and malignant disease of the prostate: critical analysis of two different test populations

OBJECTIVES: To evaluate the ability of free PSA (fPSA), total PSA (tPSA), and the free/total PSA (f/t PSA) ratio to differentiate between benign prostate disease (benign prostatic hyperplasia [BPH] and no evidence of malignancy [NEM]) and prostate cancer (CaP) using two different testing populations, and to compare predictive probabilities for the two test populations. METHODS: One test population consisted of sera from 531 men with clinically well-defined and biopsy-confirmed BPH (n = 255) or CaP (n = 276), with tPSA values ranging from 2 to 20 ng/mL. All of these serum samples were retrospective and obtained from patients evaluated in academic settings before any treatment. A second test population consisted of a prospective analysis of sera obtained from 4870 men, collected by urologists throughout the United States and processed at a single pathology laboratory. All these patients had a systematic biopsy evaluated and diagnosed at the same pathology laboratory, with the diagnosis categorized as either NEM (n = 2961) or CaP (n = 1909). No additional information on concurrent disease or pre- or current treatment status was known for this test population. For both populations, two tPSA reflex range groups, 2 to 10 and 2 to 20 ng/mL, were evaluated. RESULTS: Both test populations benefited from the application of either fPSA alone or the f/t PSA ratio to differentiate benign from malignant disease (t test P value less than 0.001). The receiver operating characteristic (ROC) curve for the f/t PSA ratio had an area under the curve (AUC) of 72% for n = 531 versus 63% for n = 4870, irrespective of the tPSA reflex range. Average fPSA values demonstrated a linear correlation to a range of tPSA concentrations for both test populations. Predictive probabilities (adjusted for established cancer prevalence rates in the academic population [n = 531]) calculated using f/t PSA ratios also demonstrated their value in contrasting the performance characteristics in the two test populations. CONCLUSIONS: The fPSA and f/t PSA ratio improved the differentiation of benign disease and CaP in two different patient samples. The f/t PSA ratio demonstrated an increased sensitivity and specificity when applied to differentiate clinically well-defined BPH and CaP (n = 531). The differences in the results between the two test samples are probably attributable to the variability of the patient's disease and treatment status in the larger, less refined, community-based population. The use of predictive probabilities provides the opportunity to provide patient-specific cancer probabilities instead of using population-based specific single cutoffs.     

Effect of prostatic biopsy on free-to-total prostate-specific antigen ratio in patients with prostate cancer

BACKGROUND: We determined the effect of prostatic biopsy on the changes in total and free prostate-specific antigen (PSA) and free-to-total PSA ratio (F/T ratio) and examined if there are differences in these parameters between patients with benign and malignant histologic findings. METHODS: The concentration of total and free PSA and the F/T ratio were determined in 35 men before and 1 h after prostatic biopsy. The level of PSA was measured with a chemiluminescent enzyme assay. Of 35 patients, nine were diagnosed as having prostate cancer. RESULTS: In patients whose biopsy revealed cancer, the F/T ratio was lower than those without cancer, although there were no differences in total and free PSA value before prostatic biopsy. One hour after prostatic biopsy, there was an increase in the level of total and free PSA and the F/T ratio in all men. The increase in the F/T ratio was greater in patients whose biopsies revealed no prostate cancer. In patients with stage B cancer, these parameters increased more than those with stage C/D cancer. CONCLUSION: Prostatic biopsy causes a dramatic increase in total and free PSA. The F/T ratio also increased after biopsy. The PSA response to prostatic biopsy might be different in patients with and without prostatic malignancy. The response might also be different according to stage of prostate cancer.     

Effect of NIH-IV prostatitis on free and free-to-total PSA

OBJECTIVE: To examine the effect of asymptomatic prostatic inflammation (NIH category IV prostatitis) on total PSA (tPSA), free serum PSA (fPSA) and the ratio of free-to-total prostate specific antigen (%fPSA). The role of free and %fPSA as a diagnostic tool for distinguishing between cancer and non-malignant diseases of the prostate was also investigated. MATERIAL AND METHODS: In a retrospective study 1090 prostate biopsies performed between January 2000 and September 2003 were evaluated and the levels of serum total and free PSA as well as the f/tPSA ratio were determined in samples obtained immediately before biopsy. 404 patients with full clinical and histological records were included in the study. All patients underwent 6 or 8 core primary prostate needle biopsies. RESULTS: A total of 404 patients were included in the analysis. 100 prostate cancer (PCa) (24.8%), 137 NIH-IV prostatitis (33.9%) and 143 patients with benign prostatic hyperplasias (BPH) (35.4%) were identified. 24 (5.9%) patients presented with both PCa and prostatitis on histology and were excluded from further analysis. The mean (median) levels of tPSA, fPSA and %fPSA were 11.94 ng/ml (8.0), 1.31 ng/ml (1.07) and 0.15 (0.14) for NIH-IV prostatitis; 11.94 ng/ml (8.35), 1.54 ng/ml and 0.13 (0.11) for prostate cancer; and 8.19 ng/ml (7.0), 1.48 ng/ml (1.03) and 0.18 (0.15) for BPH. No significant difference was found in tPSA levels between PCa and prostatitis (p = 0.32), while the difference in tPSA levels between PCa and BPH was significant (p = 0.007). Free PSA alone had no diagnostic power in distinguishing PCa from prostatitis (p = 0. 37) and BPH (p = 0. 61). By contrast, the f/tPSA ratio showed significant between-group differences (PCa versus prostatitis (p = 0. 011), PCa versus BPH (p = 0.0001). CONCLUSIONS: Chronic asymptomatic prostatitis NIH category IV has similar effects on total PSA and free PSA levels in serum as PCa. fPSA alone cannot distinguish prostate cancer from non-malignant inflammatory disease of the prostate. The ratio of free-to-total PSA is significantly different in PCa and NIH category IV prostatitis.     

Circulating tumour-associated plasma DNA represents an independent and informative predictor of prostate cancer

OBJECTIVE: To investigate whether preoperative plasma levels of free DNA can discriminate between men with localized prostate cancer and benign prostatic hyperplasia (BPH). PATIENTS AND METHODS: In all, 161 referred patients suspicious for prostate cancer either by an elevated prostate-specific antigen (PSA) level and/or abnormal digital rectal examination (DRE) were included in this prospective study. Peripheral plasma was taken before prostate biopsy and genomic DNA was extracted from the plasma using the a commercial kit and a vacuum chamber. After controlling for age, PSA level, the percentage free/total (f/t) PSA and prostate volume, the median prostate cancer plasma DNA concentration served as diagnostic threshold in uni- and multivariate logistic regression models. Multivariate models were subjected to 200 bootstraps for internal validation and to reduce over-fit bias. RESULTS: Subgroups consisted of 142 men with clinically localized prostate cancer and 19 with BPH. The median plasma concentration of cell-free DNA was 267 ng/mL in men with BPH vs 709 ng/mL in men with prostate cancer. In univariate analyses, plasma DNA concentration was a statistically significant and informative predictor (P = 0.032 and predictive accuracy 0.643). In multivariate analyses, it remained statistically significant after controlling for age, tPSA, f/tPSA and prostate volume, increasing the predictive accuracy by 5.6%. CONCLUSIONS: Our data suggest that plasma DNA level is a highly accurate and informative predictor in uni- and multivariate models for the presence of prostate cancer on needle biopsy. The predictive accuracy was substantially increased by adding plasma DNA level. However, larger-scale studies are needed to further confirm its clinical impact on prostate cancer detection.     

Diagnostic accuracy of percent free prostate-specific antigen in prostatic pathology and its usefulness in monitoring prostatic cancer patients.

INTRODUCTION: The aim of our study was to evaluate the clinical usefulness of percent free prostate-specific antigen (PSA) [ratio of free PSA (fPSA) to total PSA (tPSA); f/tPSA] in prostatic pathology and its usefulness in monitoring prostatic cancer patients. PATIENTS AND METHODS: Our prospective study was carried out on 470 consecutive male patients referred to our outpatient urological clinic for observation. We looked for relationships between tPSA, fPSA and percent free PSA and the patient's age, prostatic volume and histologic diagnosis as assessed by prostatic biopsies or surgical specimens (benign prostatic hypertrophy, carcinoma, hypertrophy with inflammation). In all cases, we calculated the specificity, sensitivity and diagnostic accuracy of percent free PSA in the diagnosis of prostatic diseases, using cutoff values ranging from 14 to 20%. In prostatic cancer patients, we considered the relationships between the various PSA molecular forms and staging, grading and follow-up values. We also evaluated the effects of hormonosuppressive therapy on the serum markers and noted for which tPSA value percent free PSA possessed the greatest diagnostic accuracy. RESULTS: While tPSA and fPSA values appeared to be correlated with patient age and prostatic volume, percent free PSA did not show a relationship with these parameters. The specificity, sensitivity and overall diagnostic accuracy were better assuming a 16% cutoff value for percent free PSA than with other cutoff values. Prostatic inflammation associated with benign hypertrophy can cause false positives in both tPSA and f/tPSA measurements, since 60% of these patients have an f/tPSA ratio below 16%. In diagnosing carcinoma, the diagnostic accuracy of percent free PSA is 100% when tPSA is between 2.5 and 4.0 ng/ml. Percent free PSA is not linked with staging in prostatic cancer, but it does appear to be related to the Gleason score. In patients receiving hormonosuppressive treatment, f/tPSA decreased significantly, and more so in patients with a higher Gleason score. In patients with disease in rapid progression, percent free PSA was lower than in patients in a stable condition. CONCLUSIONS: Based on our experience, 16% as the f/tPSA cutoff value for discriminating between benign and malignant pathologies is the best possible choice, as it provides the highest overall values of sensitivity, specificity and diagnostic accuracy (80, 61.5 and 84.5%, respectively) in the diagnosis of prostatic cancer. We believe that f/tPSA is not a definitive test for diagnosing prostatic cancer. Our observations on the behavior of percent free PSA in relation to prostatic carcinoma grading and staging and in the follow-up of carcinoma patients are interesting; however, further studies are needed to define the appropriate role of f/tPSA in patients with an established diagnosis of prostatic carcinoma and in the follow-up of patients with prostatic cancer.     

Comparative evaluation of various prostate specific antigen ratios for the early detection of prostate cancer

OBJECTIVE: To compare the performance of various ratios using total prostate specific antigen (PSA), complexed PSA (cPSA) and free PSA (fPSA) in the early detection of prostate cancer. PATIENTS AND METHODS: The study included 535 consecutive patients evaluated at a prostate cancer detection clinic between January 1998 and October 1999. Patients had blood samples drawn before transrectal ultrasonography and prostate biopsy to measure PSA, cPSA and fPSA. Receiver operating characteristic (ROC) curves (sensitivity vs 1 - specificity) were used to evaluate the performance of PSA, cPSA, f/tPSA, cPSA/tPSA, fPSA/cPSA, tPSA/prostate volume (PV), fPSA/PV, and cPSA/PV. The areas under the curve (AUC) were calculated for each ratio. The performance of each ratio over all patients or in those with a tPSA of 4-6 or 4-10 ng/mL were evaluated. RESULTS: Of the 535 patients, 204 (38%) had biopsy-confirmed prostate cancer. The AUC obtained with tPSA alone was 0.64; when measured for all patients the cPSA/PV (0.78), PSA/PV (0.77), f/tPSA (0.76) and fPSA/cPSA (0.75) performed better than tPSA alone. Furthermore, in patients with a tPSA of 4-10 ng/mL, tPSA/PV (0.72), cPSA/PV (0.71), f/tPSA (0.69), fPSA/cPSA (0.69) and cPSA/tPSA (0.62) performed better than tPSA alone (0.52). Finally, in patients with a tPSA of 4-6 ng/mL, PSA/PV and cPSA/PV performed better than the other ratios. CONCLUSIONS: The use of PSA ratios gives a higher sensitivity and specificity for detecting prostate cancer than the use of tPSA alone.     

游离PSA与总PSA比值在前列腺癌鉴别诊断中的意义

目的　探讨游离前列腺特异性抗原 (fPSA)与总前列腺特异性抗原 (tPSA)比值 (f tPSA)在tPSA为 4～ 10ng ml时对前列腺癌和良性前列腺增生 (BPH)鉴别的意义及其局限性。方法　对1998年 10月至 2 0 0 2年 10月接受诊治的 180例血清tPSA为 4～ 10ng ml的前列腺癌和BPH患者进行回顾性分析。经组织学证实 ,36例 (2 0 % )是前列腺癌 ,14 4例 (80 % )是BPH。血清中tPSA和fPSA通过酶免微粒子捕捉法测定。前列腺体积通过经腹壁超声测定。前列腺癌与BPH组间比较用t检验。采用Pearson相关系数分析前列腺体积与f tPSA之间的相关性。结果　前列腺癌患者的tPSA、f tPSA平均值分别是 6 75ng ml与 0 17;BPH患者则是 6 4 8ng ml和 0 2 5。两组患者的tPSA差异无显著意义 (P >0 0 5 ) ,而前列腺癌患者的f tPSA值显著低于BPH患者 (P <0 0 1)。此外 ,两组患者的前列腺体积与f tPSA均呈显著正相关 (前列腺癌组相关系数r=0 5 0 ,P <0 0 1;BPH组r=0 2 4 ,P <0 0 1)。在前列腺体积小于 4 0cm3,两组患者的f tPSA差异有显著意义 (P <0 0 5 ) ,当体积超过 4 0cm3,则差异无显著意义 (P >0 0 5 )。结论　f tPSA对tPSA在 4～ 10ng ml之间的前列腺癌和BPH的鉴别诊断有重要意义 ,但由于受前列腺体积的影响 ,只有在     

Influence of luteinizing hormone-releasing hormone analogues on serum levels of prostatic acid phosphatase and prostatic specific antigen in patients with metastatic carcinoma of the prostate

Serum concentrations of luteinizing hormone (LH), testosterone, prostatic acid phosphatase (PAP) and prostatic specific antigen (PSA) were measured in 16 patients with advanced prostatic cancer before and after treatment with luteinizing hormone-releasing hormone (LHRH) analogue. An initial rise of serum LH and testosterone levels was observed on day 2 of the treatment. Subsequently, serum concentrations of PAP and PSA showed a transient increase on day 5 of the treatment. This indicates that LHRH analogues had better be given in combination with antiandrogens in patients with metastatic carcinoma of the prostate.     

Prediction of prostate cancer in extended-field biopsies of the prostate

OBJECTIVES: To assess the prediction of prostate cancer using extended-field prostatic biopsies (8-11 cores), as such biopsy protocols are recommended to increase the detection of prostate cancer, and as fewer cancers are missed this should improve the prediction of biopsy outcome from the patients' history, transrectal ultrasonography (TRUS) and serum markers. PATIENTS AND METHODS: In all, 260 patients were prospectively evaluated and 206 with a total prostate-specific antigen (PSA) level of < 20 ng/mL were included. All patients were evaluated for age, family history, lower urinary tract symptoms (LUTS), medication for LUTS, previous prostate biopsy, the presence of cysts, a digital rectal examination, calcifications or hypoechoic lesions on TRUS, total and transitional zone volume, total PSA (tPSA), PSA density (tPSAD), total PSA transition zone density (tPSATZD), complexed PSA (cPSA), cPSA density (cPSAD), cPSA transitional zone density (cPSATZD), free/total (f/t)PSA ratio and free/complexed PSA ratio (f/cPSA). Logistic regression was used to predict the outcome; 80% of the patients were used to generate the models and 20% to test the prediction. RESULTS: Two models were constructed; the most accurate contained family history, cPSA, cPSAD, cPSATZD, f/cPSA, PSAD and tPSATZD (sensitivity 91%, specificity 70%). A workable and concise model contained tPSATZD, cPSATZD and f/cPSA, and had a sensitivity of 93% and a specificity of 60%. The best single predictor was tPSATZD with a sensitivity of 92% and a specificity of 55%. Using regression models can produce considerable gains in specificity. This would allow unnecessary prostate biopsies to be avoided for a third of patients compared with tPSA alone. CONCLUSIONS: The present analysis for PSA indices appeared to be slightly more accurate than those in previously published studies. Most of this improvement in diagnostic accuracy was ascribed to the use of an extended-field biopsy protocol. Prostate cancer in a first-degree relative was the only variable that contributed significantly to the regression model. tPSATZD was the best volume-adjusted PSA index. The f/tPSA appeared to be the best test with no volume adjustment, followed by f/cPSA and cPSA. Although the models are cumbersome and expensive for use in general urological practice they could be used to optimize biopsy strategies on the basis of predicted cancer probabilities in screening studies. The cost of the models may compare favourably with tPSA because of the high specificity that can be achieved.