Determination and analysis of antigenic epitopes of prostate specific antigen (PSA) and human glandular kallikrein 2 (hK2) using synthetic peptides and computer modeling.

Prostate specific antigen (PSA) and human glandular kallikrein 2 (hK2), produced essentially by the prostate gland, are 237-amino acid monomeric proteins, with 79% identity in primary structure. Twenty-five anti-PSA monoclonal antibodies (Mabs) were studied for binding to a large array of synthetic linear peptides selected from computer models of PSA and hK2, as well as to biotinylated peptides covering the entire PSA sequence. Sixteen of the Mabs were bound to linear peptides forming four independent binding regions (I-IV). Binding region I was localized to amino acid residues 1-13 (identical sequence for PSA and hK2), II (a and b) was localized to residues 53-64, III (a and b) was localized to residues 80-91 (= kallikrein loop), and IV was localized to residues 151-164. Mabs binding to regions I and IIa were reactive with free PSA, PSA-ACT complex, and with hK2; Mabs binding to regions IIb, IIIa, and IV were reactive with free PSA and PSA-ACT complex, but unreactive with hK2; Mabs binding to region IIIb detected free PSA only. All Mabs tested (n = 7) specific for free PSA reacted with kallikrein loop (binding region IIIb). The presence of Mabs interacting with binding region I did not inhibit the catalytic activity of PSA, whereas Mabs interacting with other binding regions inhibited the catalysis. Theoretical model structures of PSA, hK2, and the PSA-ACT complex were combined with the presented data to suggest an overall orientation of PSA with regard to ACT.     

前列腺特异性抗原在前列腺癌诊断中的应用进展

已经证明,前列腺特异性抗原（PSA）是一种有价值的前列腺癌（PCa)肿瘤标记物,血清PSA的广泛使用提高了前列腺癌的检出率,使晚期癌患得明显减少。然而,PSA对PCa的检测缺乏特异性,由于其高的假阳性率,引起许多不必要的活检。为了提高PSA对PCa诊断的特异性,降低不必要的活检,众多学正在探讨与PSA相关的几项参数的临床应用价值,本就此作一综述。     

Age-Specific Cutoff Value for the Application of Percent Free Prostate-Specific Antigen (PSA) in Chinese Men with Serum PSA Levels of 4.0–10.0 ng/ml

Objective

The influence of age on the performance of percent free prostate-specific antigen (%fPSA) in diagnosing prostate cancer (PCa) in East Asians is controversial. We tested the diagnostic performance of %fPSA in a multi-center biopsy cohort in China and identified the proper age-specific cutoff values to avoid unnecessary biopsies.

Methods

Consecutive patients with a prostate-specific antigen (PSA) level of 4.0–10.0 ng/ml or 10.1–20.0 ng/ml who underwent transrectal ultrasound-guided or transperineal prostate biopsy were enrolled from 22 Chinese medical centers from Jan 1, 2010 to Dec 31, 2013. The diagnostic accuracy of PSA and %fPSA was determined using the area under the receiver operating characteristic (ROC) curve (AUC). Age-specific cutoff values were calculated using ROC curve analysis.

Results

The median %fPSA was much lower in younger patients compared with older patients with a PSA level of 4.0–10.0 ng/ml or 10.1–20.0 ng/ml. The AUC of %fPSA was higher than PSA only in older patients. In patients aged 50 to 59 years, %fPSA failed to improve the diagnosis compared with PSA in these two PSA ranges. Age-specific cutoff values were 24%, 27% and 32% for patients aged 60–69, 70–79 and ≥80 years, respectively, to reduce unnecessary biopsies in men with PSA levels of 4.0–10.0 ng/ml to detect 90% of all PCa.

Conclusions

The effectiveness of %fPSA is correlated with age in the Chinese population. Age-specific cutoff values would help avoid unnecessary biopsies in the Chinese population.     

Developing a Follow-Up Strategy for Patients with PSA Ranging from 4 to 10 ng/ml via a New Model to Reduce Unnecessary Prostate Biopsies

Objective

The aim of this study was to develop a follow-up strategy based on the new model to reduce unnecessary prostate biopsies in patients with prostate specific antigen (PSA) ranging from 4 to 10 ng/ml.

Methods

A total of 436 patients with PSA ranging from 4 to 10 ng/ml who had undergone transrectal ultrasound (TRUS)-guided prostate biopsy were evaluated during the first stage. Age, PSA, free PSA (fPSA), digital rectal examination (DRE) findings, ultrasonic hypoechoic mass, ultrasonic microcalcifications, prostate volume (PV) and PSA density (PSAD) were considered as predictive factors. A multiple logistic regression analysis involving a backward elimination selection procedure was applied to select independent predictors. After a comprehensive analysis of all results, we developed a new model to assess the risk of prostate cancer and an effective follow-up strategy.

Results

Age, PSA, PV, fPSA, rate of abnormal DRE findings and rate of hypoechoic masses detected by TRUS were included in our model. A significantly greater area under the receiver-operating characteristic curve was obtained in our model when compared with using PSA alone (0.782 vs. 0.566). Patients were grouped according to the value of prostate cancer risk (PCaR). In the second stage of our study, patients with PCaR>0.52 were recommended to undergo biopsies immediately while the rest of the patients continued close follow-up observation. Compared with the first stage, the detection rate of PCa in the second stage was significantly increased (33.0% vs 21.1%, p = 0.012). There was no significant difference between the two stages in distribution of the Gleason score (p = 0.808).

Conclusions

We developed a follow-up strategy based on the new model, which reduced unnecessary prostate biopsies without delaying patients’ diagnoses and treatments.     

Effect of antibiotic treatment on serum PSA and percent free PSA levels in patients with biochemical criteria for prostate biopsy and previous lower urinary tract infections

BACKGROUND: Controversy exists as to the influence of inflammatory foci on total and free prostate-specific antigen (PSA) concentrations. The objective was to analyze the biological variations of PSA and percent free PSA (%f-PSA) in patients with biochemical criteria for prostate biopsy (PSA higher than 4 ng/mL and normal rectal examination) and compare them with the variation induced by antibiotic treatment in a cohort of patients with a history of lower urinary tract infections and no clinical evidence of prostatitis. METHODS: Ninety patients with a history of lower urinary tract infections, non-suspicious digital rectal examination and PSA between 4 and 20 ng/mL were analyzed. PSA concentration and %f-PSA were determined. Forty-five patients were treated with three weeks of ofloxacin, following which marker determination was repeated. All patients underwent ultrasound-controlled transrectal six-core prostate biopsy. RESULTS: Sixty-seven patients presented benign prostatic hyperplasia (BPH) (30 with prostatitic foci) and 23 cancer. Significant variations in PSA (6.97 ng/mL vs. 5.82 ng/mL, p=0.001) and %f-PSA (14.84% vs. 17.53%, p=0.01) were found only in the treated patients. These differences were significant for patients with BPH-associated prostatitic foci and not for patients with BPH or cancer. The tendency was for PSA to decrease (15 treated patients with PSA <4 ng/mL vs. six non-treated patients) and for %f-PSA to increase. The median variation of %f-PSA was greater than that of PSA. When the cutoff for %f-PSA was set at 25%, 18.9% of unnecessary biopsies after the first determination and 20% after the second could be avoided. By associating the reduction in PSA, up to 46% could be avoided in treated patients. CONCLUSION: Biochemical criteria for prostate biopsy may be modified in patients with a history of lower urinary tract infections due to variations greater than those explained by intraindividual biological variations, and may be influenced by the antibiotic treatment. These results suggest that subclinical inflammatory foci may influence PSA and %f-PSA.     

Structural investigation of the alpha-1-antichymotrypsin: prostate-specific antigen complex by comparative model building.

Prostate-specific antigen (PSA), produced by prostate cells, provides an excellent serum marker for prostate cancer. It belongs to the human kallikrein family of enzymes, a second prostate-derived member of which is human glandular kallikrein-1 (hK2). Active PSA and hK2 are both 237-residue kallikrein-like proteases, based on sequence homology. An hK2 model structure based on the serine protease fold is presented and compared to PSA and six other serine proteases in order to analyze in depth the role of the surface-accessible loops surrounding the active site. The results show that PSA and hK2 share extensive structural similarity and that most amino acid replacements are centered on the loops surrounding the active site. Furthermore, the electrostatic potential surfaces are very similar for PSA and hK2. PSA interacts with at least two serine protease inhibitors (serpins): alpha-1-antichymotrypsin (ACT) and protein C inhibitor (PCI). Three-dimensional model structures of the uncleaved ACT molecule were developed based upon the recent X-ray structure of uncleaved antithrombin. The serpin was docked both to PSA and hK2. Amino acid replacements and electrostatic complementarities indicate that the overall orientation of the proteins in these complexes is reasonable. In order to investigate PSA's heparin interaction sites, electrostatic computations were carried out on PSA, hK2, protein C, ACT, and PCI. Two heparin binding sites are suggested on the PSA surface and could explain the enhanced complex formation between PSA and PCI, while inhibiting the formation of the ACT-PSA complex, PSA, hK2, and their preliminary complexes with ACT should facilitate the understanding and prediction of structural and functional properties for these important proteins also with respect to prostate diseases.     

Enzymatic action of human glandular kallikrein 2 (hK2). Substrate specificity and regulation by Zn2+ and extracellular protease inhibitors.

Human glandular kallikrein 2 (hK2) is a serine protease expressed by the prostate gland with 80% identity in primary structure to prostate-specific antigen (PSA). Recently, hK2 was shown to activate the zymogen form of PSA (proPSA) in vitro and is likely to be the physiological activator of PSA in the prostate. hK2 is also able to activate urokinase and effectively cleave fibronectin. We studied the substrate specificity of hK2 and regulation of its activity by zinc and extracellular protease inhibitors present in the prostate and seminal plasma. The enzymatic activity and substrate specificity was studied by determining hK2 cleavage sites in the major gel proteins in semen, semenogelin I and II, and by measuring hydrolysis of various tripeptide aminomethylcoumarin substrates. HK2 cleaves substrates C-terminal of single or double arginines. Basic amino acids were also occasionally found at several other positions N-terminal of the cleavage site. Therefore, the substrate specificity of hK2 fits in well with that of a processor of protein precursors. Possible regulation mechanisms were studied by testing the ability of Zn2+ and different protease inhibitors to inhibit hK2 by kinetic measurements. Inhibitory constants were determined for the most effective inhibitors PCI and Zn2+. The high affinity of PCI for hK2 (kass = 2.0 x 10(5) M-1 x s-1) and the high concentrations of PCI (4 microM) and hK2 (0.2 microM) in seminal plasma make hK2 a very likely physiological target protease for PCI. hK2 is inhibited by Zn2+ at micromolar concentrations well below the 9 mM zinc concentration found in the prostate. The enzymatic activity of hK2 is likely to be reversibly regulated by Zn2+ in prostatic fluid. This regulation may be impaired in CAP and advanced metastatic cancer resulting in lack of control of the hK2 activity and a need for other means of control.     

Production and activation of recombinant hK2 with propeptide mutations resulting in high expression levels.

Human glandular kallikrein 2 (hK2) is a serine protease expressed mainly by the prostate gland with 80% identity in primary structure to prostate specific antigen (PSA). hK2 has proven to be a useful marker of prostate cancer which can be used in combination with PSA to better discriminate between prostate cancer and benign prostate hyperplasia. The studies on hK2 have been hampered by its very low phyciological levels (6 microgram.mL-1), its close similarity to PSA, and the low expression levels obtained using recombinant procedures to produce hK2 (0.7 mg.L-1). We have now generated propeptide mutations of hK2 which can be used to isolate stable, inactive prohK2 mutants. Compared with wild-type hK2, expression of the propeptide hK2 mutants increases the expression levels up to 15-40-fold giving 10-30 mg hK2.L-1. These results indicate that the low expression levels of wild-type hK2 are related to the activation or autoactivation of the wild-type enzyme and the instability of the active protease in cell culture and possibly also in tissue. The purified mutant hK2 may be activated by either enterokinase or factor Xa to generate an enzyme for use in functional studies with the characteristics of the original wild-type protein. Further, the stable inactive mutant hK2 protein may be used for immunizations to generate novel monoclonal antibodies, used as standard material for clinical assays or in crystallization studies where large quantities of protein are required.     

Specificity profiling of seven human tissue kallikreins reveals individual subsite preferences

Human tissue kallikreins (hKs) form a family of 15 closely related (chymo)trypsin-like serine proteinases. These tissue kallikreins are expressed in a wide range of tissues including the central nervous system, the salivary gland, and endocrine-regulated tissues, such as prostate, breast, or testis, and may have diverse physiological functions. For several tissue kallikreins, a clear correlation has been established between expression and different types of cancer. For example, the prostate-specific antigen (PSA or hK3) serves as tumor marker and is used to monitor therapy response. Using a novel strategy, we have cloned, expressed in Escherichia coli or in insect cells, refolded, activated, and purified the seven human tissue kallikreins hK3/PSA, hK4, hK5, hK6, hK7, hK10, and hK11. Moreover, we have determined their extended substrate specificity for the nonprime side using a positional scanning combinatorial library of tetrapeptide substrates. hK3/PSA and hK7 exhibited a chymotrypsin-like specificity preferring large hydrophobic or polar residues at the P1 position. In contrast, hK4, hK5, and less stringent hK6 displayed a trypsin-like specificity with strong preference for P1-Arg, whereas hK10 and hK11 showed an ambivalent specificity, accepting both basic and large aliphatic P1 residues. The extended substrate specificity profiles are in good agreement with known substrate cleavage sites but also in accord with experimentally solved (hK4, hK6, and hK7) or modeled structures. The specificity profiles may lead to a better understanding of human tissue kallikrein functions and assist in identifying their physiological protein substrates as well as in designing more selective inhibitors.     

Selective recognition of enzymatically active prostate-specific antigen (PSA) by anti-PSA monoclonal antibodies

Prostate-specific antigen (PSA) is widely used as a serum marker for the diagnosis of prostate cancer. To evaluate two anti-free PSA monoclonal antibodies (mAbs) as potential tools in new generations of more relevant PSA assays, we report here their properties towards the recognition of specific forms of free PSA in seminal fluids, LNCaP supernatants, 'non-binding' PSA and sera from cancer patients. PSA from these different origins was immunopurified by the two anti-free PSA mAbs (5D3D11 and 6C8D8) as well as by an anti-total PSA mAb. The composition of the different immunopurified PSA fractions was analysed and their respective enzymatic activities were determined. In seminal fluid, enzymatically active PSA was equally purified with the three mAbs. In LNCaP supernatants and human sera, 5D3D11 immunopurified active PSA mainly, whereas 6C8D8 immunopurified PSA with residual activity. In sera of prostate cancer patients, we identified the presence of a mature inactive PSA form which can be activated into active PSA by use of high saline concentration or capture by an anti-total PSA mAb capable of enhancing PSA activity. According to PSA models built by comparative modelling with the crystal structure of horse prostate kallikrein described previously, we assume that active and activable PSA could correspond to mature intact PSA with open and closed conformations of the kallikrein loop. The specificity of 5D3D11 was restricted to both active and activable PSA, whereas 6C8D8 recognized all free PSA including intact PSA, proforms and internally cleaved PSA.     

经直肠剪切波弹性成像技术联合血清CEA、PSA、FPSA对前列腺良恶性病变的鉴别诊断价值研究

摘要 目的：研究经直肠剪切波弹性成像技术（TRSWE）联合血清癌胚抗原（CEA）、前列腺特异性抗原（PSA）、游离前列腺特异性抗原（FPSA）对前列腺良恶性病变的鉴别诊断价值。方法：选取合肥市第二人民医院2019年1月～2022年6月收治的90例前列腺病变患者,根据病理检查分为前列腺癌组（47例）和前列腺良性病变组（43例）。对所有前列腺病变患者均行TRSWE检查,分析前列腺良恶性病变的图像差异以及弹性模量最大值（Emax）、弹性模量平均值（Emean）。检测所有前列腺病变患者的血清CEA、PSA、FPSA水平并进行对比。采用受试者工作特征（ROC）曲线分析明确Emax值、Emean值以及血清CEA、PSA、FPSA水平联合诊断前列腺良恶性病变的效能。结果：前列腺癌组Emax值、Emean值均高于前列腺良性病变组（均P＜0.05）。前列腺癌组血清CEA、PSA及FPSA水平均高于前列腺良性病变组（均P＜0.05）。经ROC曲线分析发现,Emax值、Emean值以及血清CEA、PSA、FPSA水平联合检测诊断前列腺良恶性病变的效能优于上述5项指标单独检测。结论：TRSWE联合血清CEA、PSA、FPSA对前列腺良恶性病变的鉴别诊断价值较高,可有效提升前列腺癌的检出率,可能值得临床推广应用。     

Prostate-specific antigen levels among cirrhotic patients

PURPOSE: The aim of this study was to determine serum prostate-specific antigen (PSA) levels in patients with liver cirrhosis. PATIENTS AND METHODS: Between January 1995 and August 2001, 216 men with cirrhosis were evaluated. The extent of their liver disease was classified according to the Child-Pugh classification. Serum PSA levels were measured with the Hybritech Tandem-R RIA method and matched with age-related reference PSA levels. Digital rectal examination (DRE) was performed in all patients. Patients with elevated PSA levels and/or abnormal DRE were recommended to undergo further assessment including transrectal ultrasonography (TRUS) and biopsy performed by an urologist. RESULTS: Two hundred and sixteen men (mean age 54.09 +/- 9.09 years, range 25-76) with cirrhosis were examined. Their mean PSA value was 0.57 +/- 0.84 ng/mL and tended to be lower than in the normal population. The degree of PSA decrease was found to parallel the severity of the liver disease (p=0.002). The mean serum PSA level increased with each age decade in a statistically significant manner (p<0.001). Four patients (three with elevated PSA values) underwent prostate biopsy. Three biopsies were positive for prostate cancer, the other showed evidence of benign prostatic hyperplasia (BPH). CONCLUSION: Serum PSA is influenced by the severity of liver disease and its levels tend to be lower in cirrhotic patients than in the normal population. However, serum PSA can still be considered a reliable marker in the clinical management of prostatic disease in patients with cirrhosis.     

Reproducibility,Performance, and Clinical Utility of a Genetic Risk Prediction Model for Prostate Cancer in Japanese

Prostate specific antigen (PSA) is widely used as a diagnostic biomarker for prostate cancer (PC). However, due to its low predictive performance, many patients without PC suffer from the harms of unnecessary prostate needle biopsies. The present study aims to evaluate the reproducibility and performance of a genetic risk prediction model in Japanese and estimate its utility as a diagnostic biomarker in a clinical scenario. We created a logistic regression model incorporating 16 SNPs that were significantly associated with PC in a genome-wide association study of Japanese population using 689 cases and 749 male controls. The model was validated by two independent sets of Japanese samples comprising 3,294 cases and 6,281 male controls. The areas under curve (AUC) of the model were 0.679, 0.655, and 0.661 for the samples used to create the model and those used for validation. The AUCs were not significantly altered in samples with PSA 1–10 ng/ml. 24.2% and 9.7% of the patients had odds ratio <0.5 (low risk) or >2 (high risk) in the model. Assuming the overall positive rate of prostate needle biopsies to be 20%, the positive biopsy rates were 10.7% and 42.4% for the low and high genetic risk groups respectively. Our genetic risk prediction model for PC was highly reproducible, and its predictive performance was not influenced by PSA. The model could have a potential to affect clinical decision when it is applied to patients with gray-zone PSA, which should be confirmed in future clinical studies.     

Large-scale propagation of recombinant adherent cells that secrete a stable form of human glandular kallikrein, hK2

Human glandular kallikrein 2 (hK2) is a trypsin-like serine protease that is expressed predominantly in the prostate epithelium and has 78% aa identity with prostate-specific antigen (PSA). hK2 has been recognized as a potential prostate cancer marker and has been demonstrated to be highly expressed in prostate cancer compared to benign prostatic tissue. Purification and characterization of hK2 have been impeded due to its lower expression in bodily fluids and tissues compared to PSA and its ability to autodegrade. Therefore, to study biochemical and biological characteristics of hK2, a stable and enzymatically inactive mutant form of hK2, hK2(A217V), was expressed in a hamster cell line, AV12-664 (AV12-hK2(A217V)). AV12-hK2(A217V) cells secreted prohK2(A217V) (phK2(A217V)) in the spent medium at approximately 2.5 microgram/ml. Since AV12-hK2(A217V) are adherent cells, it was necessary to develop an efficient system to propagate large numbers of cells to obtain significant quantities of phK2(A217V). In this paper, we compared ceramic core bioreactor and microcarrier beads as alternatives to static culture to propagate adherent cells. Considering production levels, ease of operation, cost effectiveness, and labor, microcarrier beads were found to be a better alternative. Our findings led to the development of a general protocol for large-scale propagation of adherent cells on microcarrier beads eliminating the need for propagating AV12-hK2(A217V) in culture flasks or bioreactors. Microcarrier beads coated with AV12-hK2(A217V) cells could be propagated in 1- or 3-liter spinner flasks and were passed from one spinner to the next in a manner analogous to static culture or could be frozen and later used as inoculum for subsequent spinners. Using this protocol, >40 liters of spent medium was harvested within 30 days, which in turn was used to purify phK2(A217V). phK2(A217V) purified from spent medium of cells grown either on microcarrier beads or in culture flasks were biochemically similar as indicated by HIC-HPLC profile followed by sequencing of relevant peaks.     

Two step procedure for purification of enzymatically active prostate-specific antigen from seminal plasma

The role of prostate-specific antigen (PSA) during the onset of prostate cancer and subsequent tumor growth and metastasis is not well understood. We have developed a simple two step procedure, based on principles of hydrophobic charge-induction chromatography and molecular size chromatography to provide pure free-PSA (f-PSA) preparation that is free from all other known PSA complexes as well as human kallikrein 2 (hK2). The overall recovery of f-PSA is 72%. The isolated f-PSA consists of three known isoforms that corresponds to pI of 6.2, 6.4 and 7.2. f-PSA is enzymatically active and its enzymatic activity can be effectively neutralized by a serine protease inhibitor.     

Optimisation de l’utilisation du PSA

PSA is a tumor marker usually determined for prostate cancer at diagnosis for its pronostic value and at therapy follow-up. But lack of specificity of PSA for prostate cancer and variability between assays demonstrated by the quality program survey make this marker not valuable in mass screening program. Market control of Afssaps on analysis devices of PSA showed a correct harmonization for total PSA. Biological tools available and easy to perform could improve ability of PSA for early detection of prostate cancer at a curable stage without induction of unnecessary biopsies prescribed because elevated total PSA values.     

Secretion of endogenous kallikreins 2 and 3 by androgen receptor-transfected PC-3 prostate cancer cells

Androgen independent PC-3 cells lack androgen receptor (AR) expression and do not produce kallikrein 2 (hK2) or 3 (prostate-specific antigen, PSA). In this paper, we examined the ability of androgens to stimulate PSA and hK2 production in AR transfected PC-3 cells (PC-3(AR)) and compared this to LNCaP cells. PSA and hK2 were measured in the culture medium and cell lysates using an ELISA-based immunofluorometric assay. Only androgens were able to induce PSA and hK2 secretion in PC-3(AR) cells in a dose- and time-dependent manner depending on the level of AR present. The level of androgen-induced PSA and hK2 secretion in PC-3(AR) cells was approximately 1.5 and 0.9% that induced in LNCaP cells, respectively. Insulin-like growth factor-I (IGF-I), which has been shown to activate AR in the absence of ligand, did not activate PSA secretion in the absence of androgen, but further increased the dihydrotestosterone-induced PSA secretion in PC-3(AR) cells. The lack of PSA and hK2 production in parental PC-3 cells is thus a result of their lack of AR expression. PSA and/or hK2 production in PC-3(AR) cells can thus serve as an endogenous reporter system to investigate AR action or to screen putative endocrine disrupters.     

Traitement par ultrasons focalisés du cancer localisé de la prostate: Résultats carcinologiques et pronostic sexuel

Introduction

Since 1999, a therapeutic device using High Intensity Focused Ultrasound (HIFU) technology has been marketed in Europe for the treatment of localized prostate cancer. Clinical and technical development was designed to provide a minimally invasive alternative for these patients. The purpose of this study was to evaluate the efficacy of HIFU therapy for localized prostate cancer and its impact on sexual function.

Material and Methods

HIFU technology is based on a convergent beam of high intensity ultrasound that creates a sudden and sharp increase in temperature (85°C to 100°C) in the tissues at the focal point. This leads to a precise lesion in the tissue, adjustable from 19 to 24 mm in height and 2 mm in diameter. Successive displacements of the focal point are computer-driven, allowing treatment of a defined volume. All patients were treated with the ABLATHERM® device (EDAP SA, France); they were treated using the device prototypes between 1993 to 1999 and then with the marketed machine. The treatment procedure was improved from 2000 onwards with the combination of transurethral resection of the prostate (TURP) in order to reduce post-treatment catheter time. A nerve-sparing procedure was also tested in 2002. The selected population included 120 patients considered to be potentially curable with clinical stage T1–T2 prostate cancer and an initial PSA < 10 ng/ml (group 1). A larger group of 167 patients with an initial PSA < 30 ng/ml was also considered (group 2). All patients were not candidates for surgery due to their age or comorbidities. In the two groups, clinical failure was defined by the need for administration of an adjuvant prostate cancer treatment (hormone deprivation or external radiation). Disease progression, or biochemical failure, was strictly defined as any evidence of residual cancer on follow-up biopsies (regardless of the PSA level), or 3 successive increases of the PSA level (with negative follow-up biopsies), with a velocity > 0.75 ng/ml/year. Disease-free survival rates were calculated using the Kaplan-Meier method. Survival rates were compared using the log-rank test. The impact of HIFU treatment on sexual function was assessed by a questionnaire in 70 patients who underwent standard HIFU treatment and in 28 patients in whom a nerve-sparing procedure was performed.

Results

Patient baseline characteristics (± SD) were, in group 1 and group 2 respectively: mean age: 71.2 (± 5.34) years and 71.8 (± 5.11) years; clinical stage: T1 for 61 patients and T2 for 59 patients in group 1, and T1 for 77 patients, T2 for 85 patients and T3 for 5 patients in group 2; mean initial PSA level: 5.67 (± 2.47) ng/ml and 9.30 (± 6.01) ng/ml; Gleason score: 2–6 for 77 patients and 7–10 for 43 patients in group 1, and 2–6 for 98 patients, 7 for 44 patients, and 8–10 for 25 patients in group 2; mean prostate volume: 33.6 (± 16.5) ml and 34.4 (± 16.7) ml, respectively. Mean follow-up was 27 months (range: 3–96 months) in group 1, and 23 months (range: 3–90 months) in group 2. In group 1, a residual cancer was diagnosed in 17 patients, but only 6 patients needed adjuvant treatment due to a significant rise of the PSA level (hormone deprivation: n=2, external radiation: n=4), leading to a clinical success rate of 95%. Similarly, in group 2, 36 patients presented with positive follow-up biopsies, and 21 of them required adjuvant treatment (hormone deprivation: n=10, external radiation: n=11), leading to a clinical success rate of 87.5%. The disease-free survival rates (previously defined on the combined biopsy and PSA criteria) were 76.9% and 66% in group 1 and 2, respectively. In addition, the disease-free survival rate in group 2 was stratified according to the initial prognosis risk level: 85% in low-risk patients (i.e. patients with clinical stage T1–T2a and PSA < 10 ng/ml and Gleason score < 7), 67.5% in intermediate-risk patients (i.e. clinical stage T2b or PSA 10–20 ng/ml or Gleason score = 7), and 42% in high-risk patients (i.e. clinical stage T2c or PSA > 20 ng/ml or Gleason score > 7). In the overall population, 70 patients had normal sexual function prior to HIFU treatment; 25 patients (36%) still had erections allowing sexual intercourse with penetration after treatment. A nerve-sparing procedure was also performed in 28 potent patients: 43% of these patients had persistent erections allowing sexual intercourse with penetration after treatment, indicating that this nerve-sparing procedure still needs to be improved.

Conclusion

The efficacy results observed after HIFU treatment are similar to those observed after other non-surgical treatments for prostate cancer. After complete HIFU treatment of the gland, more than 1/3 of patients still reported erections allowing sexual intercourse with penetration; these results must be interpreted for an elderly population (mean age: 72 years). A nerve-sparing procedure is currently being perfected and tested.