MSH2-deficient prostate tumours have a distinct immune response and clinical outcome compared to MSH2-deficient colorectal or endometrial cancer.

BACKGROUND: Recent publications have shown patients with defects in the DNA mismatch repair (MMR) pathway driven by either MSH2 or MSH6 loss experience a significant increase in the incidence of prostate cancer. Moreover, this increased incidence of prostate cancer is accompanied by rapid disease progression and poor clinical outcomes. METHODS AND RESULTS: We show that androgen-receptor activation, a key driver of prostate carcinogenesis, can disrupt the MSH2 gene in prostate cancer. We screened tumours from two cohorts (recurrent/non-recurrent) of prostate cancer patients to confirm the loss of MSH2 protein expression and identified decreased MSH2 expression in recurrent cases. Stratifying the independent TCGA prostate cancer cohort for MSH2/6 expression revealed that patients with lower levels of MSH2/6 had significant worse outcomes, in contrast, endometrial and colorectal cancer patients with lower MSH2/6 levels. MMRd endometrial and colorectal tumours showed the expected increase in mutational burden, microsatellite instability and enhanced immune cell mobilisation but this was not evident in prostate tumours. CONCLUSIONS: We have shown that loss or reduced levels of MSH2/MSH6 protein in prostate cancer is associated with poor outcome. However, our data indicate that this is not associated with a statistically significant increase in mutational burden, microsatellite instability or immune cell mobilisation in a cohort of primary prostate cancers.

Male urethral stricture disease in a regional centre: 10 years of experience.

BACKGROUND: Male urethral stricture disease is a challenging condition with a propensity for recurrence following endoscopic management. In recent years, earlier definitive urethral reconstruction has been advocated through international guidelines, prompted by series suggesting the underutilization of urethroplasty at rates of 0.6-0.8%. However, little local data exists to characterize our urethral stricture patients and we aimed to characterize the management of patients with urethral stricture disease presenting over a 10-year period to a single regional centre. METHODS: Patients with urethral stricture disease and admitted to a regional health service were identified. Retrospective chart review was undertaken for patients detailing basic demographics, stricture characteristics, clinical management and follow up. RESULTS: We identified 360 patients with median age 69 years (interquartile range 56-77). A total of 191 (53%) presented with lower urinary tract symptoms, 122 (34%) urethral strictures were incidental, and 13% presented in urinary retention. Bulbar urethral strictures were the commonest strictures at 40% with most being spontaneous or idiopathic (67%). A total of 339 patients had treatment during their first admission, 48% of patients had subsequent treatment on a second episode, and over 20% had a third or subsequent treatment. Only 21 (5.8%) underwent urethroplasty. Urethral dilatation and optical urethrotomy were most commonly performed (54%). With follow up 19 months (interquartile range 2-56), 205 (57%) were voiding, 38 (11%) were performing intermittent catheterization, and 59 were catheterized permanently. CONCLUSION: Definitive urethral reconstruction appears underutilized in our cohort of patients. A high proportion of incidentally presenting urethral strictures emphasizes the importance of wider education to optimize patient outcomes.

3D modelling of radical prostatectomy specimens: Developing a method to quantify tumor morphometry for prostate cancer risk prediction.

Prostate cancer displays a wide spectrum of clinical behaviour from biological indolence to rapidly lethal disease, but we remain unable to accurately predict an individual tumor's future clinical course at an early curable stage. Beyond basic dimensions and volume calculations, tumor morphometry is an area that has received little attention, as it requires the analysis of the prostate gland and tumor foci in three-dimensions. Previous efforts to generate three-dimensional prostate models have required specialised graphics units and focused on the spatial distribution of tumors for optimisation of biopsy strategies rather than to generate novel morphometric variables such as tumor surface area. Here, we aimed to develop a method of creating three-dimensional models of a prostate's pathological state post radical prostatectomy that allowed the derivation of surface areas and volumes of both prostate and tumors, to assess the method's accuracy to known clinical data, and to perform initial investigation into the utility of morphometric variables in prostate cancer prognostication. Serial histology slides from 21 prostatectomy specimens covering a range of tumor sizes and pathologies were digitised. Computer generated three-dimensional models of tumor and prostate space filling models were reconstructed from these scanned images using Rhinoceros 4.0 spatial reconstruction software. Analysis of three-dimensional modelled prostate volume correlated only moderately with weak concordance to that from the clinical data (r=0.552, θ=0.405), but tumor volume correlated well with strong concordance (r=0.949, θ=0.876). We divided the cohort of 21 patients into those with features of aggressive tumor versus those without and found that larger tumor surface area (32.7 vs 3.4cc, p=0.008) and a lower tumor surface area to volume ratio (4.7 vs 15.4, p=0.008) were associated with aggressive tumor biology.

Comparing nodal versus bony metastatic spread using tumour phylogenies.

The role of lymph node metastases in distant prostate cancer dissemination and lethality is ill defined. Patients with metastases restricted to lymph nodes have a better prognosis than those with distant metastatic spread, suggesting the possibility of distinct aetiologies. To explore this, we traced patterns of cancer dissemination using tumour phylogenies inferred from genome-wide copy-number profiling of 48 samples across 3 patients with lymph node metastatic disease and 3 patients with osseous metastatic disease. Our results show that metastatic cells in regional lymph nodes originate from evolutionary advanced extraprostatic tumour cells rather than less advanced central tumour cell populations. In contrast, osseous metastases do not exhibit such a constrained developmental lineage, arising from either intra or extraprostatic tumour cell populations, at early and late stages in the evolution of the primary. Collectively, this comparison suggests that lymph node metastases may not be an intermediate developmental step for distant osseous metastases, but rather represent a distinct metastatic lineage.

Holmium Laser Enucleation of the Prostate in a 400 cc Prostate: Case Report.

The modality of choice in the surgical management of benign prostatic hyperplasia for large prostates has traditionally been open prostatectomy. Advances in minimally invasive techniques have begun to challenge this notion with advantages such as lower bleeding and transfusion rates and shorter hospital stay. In this case report, we illustrate the use of holmium laser enucleation of the prostate (HoLEP) in a gland measuring more than 400 cc. We describe the case of a 71-year-old man with persistent voiding urinary symptoms despite two previous transurethral resections of his prostate. With greater experience in HoLEP and declining experience in open prostatectomy, there may be a shift toward HoLEP as the preferred treatment choice for large prostate glands.

Waiting for definitive care: An analysis of elapsed time from decision to surgery or transfer in a rural centre.

OBJECTIVE: To examine the timing of operative management and interhospital transfer of emergency general surgical patients in a regional setting. DESIGN: Retrospective cohort study. SETTING: The surgical unit at a major rural referral centre for North-Eastern Victoria servicing a population of 90 000. PARTICIPANTS: General surgical patients (n = 649) admitted via the emergency department at Northeast Health Wangaratta between January 2011 and March 2013 undergoing operative management (n = 608) or transfer to a tertiary centre (n = 44). MAIN OUTCOME MEASURES: Timing of operative management, using appendicectomy as a benchmark operation, was measured as time from presentation to decision to operate, time from decision to surgery, percentage after-hours operating and length of stay (LOS). Time to interhospital transfer was calculated and reasons for delay were sought. RESULTS: Two hundred forty-six appendicectomies were performed. Median time from decision to operate to theatre was 3 hours (interquartile range (IQR) 2-8), and total LOS was 43 hours (IQR: 28-56). Two hundred seventy-two procedures (43%) were performed out-of-hours, including 48% of appendicectomies. Median time from decision making to transfer was 10.3 hours (IQR: 4.7-25). Transfer was less likely to be delayed in trauma patients when compared with urgent non-trauma patients (5.3 versus 10.6 hours; P = 0.04). CONCLUSION: Even in the absence of a strict four-hour rule program and a dedicated emergency surgical unit, main outcome measures appear to be comparatively efficient. However, the duration for transfer of patients is suboptimal because of the lack of established pathways for urgent non-trauma transfer from rural centres and bed availability in tertiary hospitals.

Tracking the origins and drivers of subclonal metastatic expansion in prostate cancer.

Tumour heterogeneity in primary prostate cancer is a well-established phenomenon. However, how the subclonal diversity of tumours changes during metastasis and progression to lethality is poorly understood. Here we reveal the precise direction of metastatic spread across four lethal prostate cancer patients using whole-genome and ultra-deep targeted sequencing of longitudinally collected primary and metastatic tumours. We find one case of metastatic spread to the surgical bed causing local recurrence, and another case of cross-metastatic site seeding combining with dynamic remoulding of subclonal mixtures in response to therapy. By ultra-deep sequencing end-stage blood, we detect both metastatic and primary tumour clones, even years after removal of the prostate. Analysis of mutations associated with metastasis reveals an enrichment of TP53 mutations, and additional sequencing of metastases from 19 patients demonstrates that acquisition of TP53 mutations is linked with the expansion of subclones with metastatic potential which we can detect in the blood.

Curated microRNAs in urine and blood fail to validate as predictive biomarkers for high-risk prostate cancer.

PURPOSE: The purpose of this study was to determine if microRNA profiling of urine and plasma at radical prostatectomy can distinguish potentially lethal from indolent prostate cancer. MATERIALS AND METHODS: A panel of microRNAs was profiled in the plasma of 70 patients and the urine of 33 patients collected prior to radical prostatectomy. Expression of microRNAs was correlated to the clinical endpoints at a follow-up time of 3.9 years to identify microRNAs that may predict clinical response after radical prostatectomy. A machine learning approach was applied to test the predictive ability of all microRNAs profiled in urine, plasma, and a combination of both, and global performance assessed using the area under the receiver operator characteristic curve (AUC). Validation of urinary expression of miRNAs was performed on a further independent cohort of 36 patients. RESULTS: The best predictor in plasma using eight miRs yielded only moderate predictive performance (AUC = 0.62). The best predictor of high-risk disease was achieved using miR-16, miR-21 and miR-222 measured in urine (AUC = 0.75). This combination of three microRNAs in urine was a better predictor of high-risk disease than any individual microRNA. Using a different methodology we found that this set of miRNAs was unable to predict high-volume, high-grade disease. CONCLUSIONS: Our initial findings suggested that plasma and urinary profiling of microRNAs at radical prostatectomy may allow prognostication of prostate cancer behaviour. However we found that the microRNA expression signature failed to validate in an independent cohort of patients using a different platform for PCR. This highlights the need for independent validation patient cohorts and suggests that urinary microRNA signatures at radical prostatectomy may not be a robust way to predict the course of clinical disease after definitive treatment for prostate cancer.

Canonical androstenedione reduction is the predominant source of signaling androgens in hormone-refractory prostate cancer.

PURPOSE: It has been recognized for almost a decade that concentrations of signaling androgens sufficient to activate the androgen receptor are present in castration-resistant prostate cancer tissue. The source of these androgens is highly controversial, with three competing models proposed. We, therefore, wished to determine the androgenic potential of human benign and malignant (hormone-naïve and treated) prostate tissue when incubated with various precursors and examine concomitant changes in enzyme expression. EXPERIMENTAL DESIGN: Freshly harvested prostate tissue [benign, hormone-naïve, and hormone-refractory prostate cancer (HRPC)] was incubated in excess concentrations of cholesterol, progesterone, DHEA, androstenedione, or testosterone for 96 hours, and steroid concentrations in the conditioned media measured by gas chromatography-mass spectroscopy. Changes in the expression of androgen synthetic and/or degradative enzymes were determined by expression microarray and qPCR. Significant changes were confirmed in an independent dataset. RESULTS: Of the precursor molecules tested, only incubation with androstenedione gave rise to significant concentrations of signaling androgens. Although this was observed in all tissue types, it occurred to a significantly greater degree in hormone-refractory compared with hormone-naïve cancer. Consistent with this, gene set enrichment analysis of the expression microarray data revealed significant upregulation of 17HSD17B activity, with overexpression of the canonical enzyme AKR1C3 confirmed by qPCR in the same samples and in a publicly available expression dataset. Importantly, we found no evidence to support a significant contribution from either the "backdoor" or "5-α dione" pathway. CONCLUSIONS: Reduction of androstenedione to testosterone by the canonical HSD17B AKR1C3 is the predominant source of signaling androgens in HRPC.

Reducing the risk of false discovery enabling identification of biologically significant genome-wide methylation status using the HumanMethylation450 array.

BACKGROUND: The Illumina HumanMethylation450 BeadChip (HM450K) measures the DNA methylation of 485,512 CpGs in the human genome. The technology relies on hybridization of genomic fragments to probes on the chip. However, certain genomic factors may compromise the ability to measure methylation using the array such as single nucleotide polymorphisms (SNPs), small insertions and deletions (INDELs), repetitive DNA, and regions with reduced genomic complexity. Currently, there is no clear method or pipeline for determining which of the probes on the HM450K bead array should be retained for subsequent analysis in light of these issues. RESULTS: We comprehensively assessed the effects of SNPs, INDELs, repeats and bisulfite induced reduced genomic complexity by comparing HM450K bead array results with whole genome bisulfite sequencing. We determined which CpG probes provided accurate or noisy signals. From this, we derived a set of high-quality probes that provide unadulterated measurements of DNA methylation. CONCLUSIONS: Our method significantly reduces the risk of false discoveries when using the HM450K bead array, while maximising the power of the array to detect methylation status genome-wide. Additionally, we demonstrate the utility of our method through extraction of biologically relevant epigenetic changes in prostate cancer.

Percutaneous image-guided biopsy of prostate cancer metastases yields samples suitable for genomics and personalised oncology.

Personalised oncology through mutational profiling of cancers requires the procurement of fresh frozen tumour samples for genomics applications. While primary cancers are often surgically excised and therefore yield such tissue, metastases in the setting of a known cancer diagnosis are not routinely sampled prior to systemic therapy. Our study aimed to determine the suitability of extracted nucleic acids for genomics applications using distant metastatic prostate cancer samples obtained via percutaneous or surgical biopsy. Patients with metastatic prostate cancer were recruited for image-guided biopsy of metastases. Patients undergoing surgical procedures for the complications of metastases were also recruited. Tissue samples were flash frozen and cryosectioned for histological examination. DNA and RNA were simultaneously extracted and genomic DNA hybridised onto SNP arrays for genome-wide copy number analysis. 37 samples of metastatic tissue from seven patients with prostate cancer were obtained. Five of these underwent image-guided biopsies whilst two had therapeutic surgical procedures performed. 22 biopsy samples were obtained across the image-guided biopsy patients with 80 % of samples being successfully processed for downstream analysis. Nucleic acid yield from these samples were satisfactory for genomics applications. Copy number analysis revealed a median estimated tumour purity of 53 % and all samples showed chromosomal abnormalities suggestive of malignancy. The procurement of osseous metastatic prostate cancer from live patients, including the use of image-guided biopsy, is safe and feasible. Sufficient tissue can be obtained in a manner such that extracted nucleic acids are suitable for genomics research.

Torsion of Wandering Gallbladder following Colonoscopy.

Torsion of the gallbladder is an uncommon condition that may present as an acute abdomen. Its preoperative diagnosis can often be challenging due to its variable presentation, with specific sonographic signs seen infrequently. We describe, to our knowledge, the first case of torsion of a wandering gallbladder following a colonoscopy in a 69-year-old female who presented with acute abdominal pain after procedure. This was discovered intraoperatively, and after a subsequent cholecystectomy, she had an uncomplicated recovery.

Error rates in a clinical data repository: lessons from the transition to electronic data transfer--a descriptive study.

OBJECTIVE: Data errors are a well-documented part of clinical datasets as is their potential to confound downstream analysis. In this study, we explore the reliability of manually transcribed data across different pathology fields in a prostate cancer database and also measure error rates attributable to the source data. DESIGN: Descriptive study. SETTING: Specialist urology service at a single centre in metropolitan Victoria in Australia. PARTICIPANTS: Between 2004 and 2011, 1471 patients underwent radical prostatectomy at our institution. In a large proportion of these cases, clinicopathological variables were recorded by manual data-entry. In 2011, we obtained electronic versions of the same printed pathology reports for our cohort. The data were electronically imported in parallel to any existing manual entry record enabling direct comparison between them. OUTCOME MEASURES: Error rates of manually entered data compared with electronically imported data across clinicopathological fields. RESULTS: 421 patients had at least 10 comparable pathology fields between the electronic import and manual records and were selected for study. 320 patients had concordant data between manually entered and electronically populated fields in a median of 12 pathology fields (range 10-13), indicating an outright accuracy in manually entered pathology data in 76% of patients. Across all fields, the error rate was 2.8%, while individual field error ranges from 0.5% to 6.4%. Fields in text formats were significantly more error-prone than those with direct measurements or involving numerical figures (p<0.001). 971 cases were available for review of error within the source data, with figures of 0.1-0.9%. CONCLUSIONS: While the overall rate of error was low in manually entered data, individual pathology fields were variably prone to error. High-quality pathology data can be obtained for both prospective and retrospective parts of our data repository and the electronic checking of source pathology data for error is feasible.

Haemostasis in neurosurgery: what is the evidence for gelatin-thrombin matrix sealant?

Strict intra-operative haemostasis is essential in the practice of neurosurgery. Over the last century, haemostatic methods have advanced significantly and the modern surgeon is now faced with an array of haemostatic agents, each with subtly different qualities and proven in different contexts with various levels of evidence. The popularity of endoscopic and laparoscopic procedures in other surgical specialties has encouraged the introduction of novel agents to achieve haemostasis where conventional methods have proven difficult. These agents are beginning to find a role in routine use for surgery in both the elective and emergent settings. This article reviews the mechanisms of different haemostasis methods and the current evidence for their use in neurosurgery, with a focus on the more recently introduced gelatin-thrombin matrix sealant (Floseal [Baxter, Hayward, CA, USA]).

Presence or absence of a positive pathological margin outperforms any other margin-associated variable in predicting clinically relevant biochemical recurrence in Gleason 7 prostate cancer.

UNLABELLED: WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: The presence of a positive pathological margin is an independent risk factor for clinically significant disease recurrence only in intermediate-risk disease when the a priori risk of micrometastatic disease is accounted for. The study examines patients with Gleason 7 prostate cancer to assess the relative importance of various margin-related variables (focality, linear length, tumour grade at margin, presence of diathermy artifact and plane of tumour) with regard to biochemical recurrence. We found that the presence or absence of a positive pathological margin outperforms any other margin-associated variable in predicting significant disease recurrence. OBJECTIVE: To determine the influence of pathological margin variables on the risk of clinically significant biochemical recurrence in Gleason 7 prostate cancer. MATERIALS AND METHODS: Patients with Gleason 7 prostate cancer with complete clinical and pathological data and detailed follow-up were identified from a prospectively recorded prostatectomy database. Slides from all patients with positive pathological margins were reviewed by a single expert uropathologist and the following information recorded: multifocality, linear length, predominant Gleason grade at the margin, diathermy artifact and margin plane. Cox regression models were generated to determine the impact of positive pathological margins on the risk of biochemical recurrence (using various definitions thereof). RESULTS: Of 1048 patients with Gleason 7 prostate cancer, 238 (23%) patients had positive margins. With a median follow-up of 11 months, biochemical recurrence occurred in 9.7% of patients with negative surgical margins and 28.4% of patients with positive margins. Positive margins were significantly associated with higher serum prostate-specific antigen (PSA) level, tumour grade, stage and volume. In patients with positive pathological margins, controlling for other factors, no margin-derived variable (focality, linear length, tumour grade at margin, diathermy artifact or plane of tumour) was a consistent predictor of biochemical recurrence, although the presence of Gleason score 4 or tertiary Gleason score 5 tumour at the margin edge was an independent predictor of recurrence with PSA doubling times ≤ 6 and ≤9 months. Similarly, in the cohort as a whole, the pathological margin status was a more important predictor of recurrence than any other margin-derived variable. CONCLUSIONS: In Gleason 7 prostate cancer, positive pathological margin status was the only consistent margin-derived variable determining biochemical failure. The presence of high-grade disease at the margin may also have an impact on the development of clinically significant biochemical recurrence.

Bladder cancer biorepositories in the "-omics" era: integrating quality tissue specimens with comprehensive clinical annotation.

Advances in genomic platforms have led to the need for well-characterized, high quality biospecimens for research. Bladder cancer, despite being a major epidemiological concern, has been under-represented in genomic programs due to unique challenges in collection of clinical informatics and tissues. Currently no targeted therapy exists for management of the disease. We report our experiences and lessons learnt in establishing an integrated model of bladder cancer that uses a dedicated bladder cancer team and relational databases. It streamlines both clinical activity and serial harvesting of biospecimens to obtain tissue that is consistently suitable for high-throughput genomic research. Fresh tissue, blood, and urine samples were prospectively collected and stored. RNA and DNA were extracted simultaneously, quality control was performed, and whole transcriptome sequencing also performed using the illumina series of platforms. Over a 15-month period, urine was banked for 209 patients, plasma and whole blood for 185 patients, and tissue for 71 patients. The collections included normal mucosa from patients with and without bladder cancer and cancer tissue across the entire histopathogical spectrum of bladder cancer from low-grade noninvasive cancers to metastatic lymph nodes. We used a relational database to link clinical information to tumor inventory and provide access to richly annotated specimens and matched clinical informatics. We found that tumor tissue was successfully banked more often in patients who had macroscopic papillary disease compared to those without. We also show that the median RNA integrity number (RIN) scores are significantly higher in patients whose tissues were banked using cold-cup biopsies compared to those banked using electrocautery. Transcriptome sequencing of all samples banked using cold-cup biopsies passed bioinformatics quality assessment and had a mean Q30 quality score well over the illumina quality control benchmark. Such an infrastructure will allow genomic profiling of bladder cancer to help us understand the "global picture" in bladder cancer pathogenesis.

Microscopic assessment of fresh prostate tumour specimens yields significantly increased rates of correctly annotated samples for downstream analysis.

AIMS: To assess if performing frozen sections of tissue biopsies from fresh radical prostatectomy specimens, prior to tissue banking, could improve the identification of the banked samples compared to standard fresh tumour banking procedures. METHODS: Tissue biopsies banked from 332 fresh prostatectomy specimens were assessed for accuracy of diagnosis, comparing two separate methods of tumour identification: one in which tumour was identified in the gross specimen by visual inspection (n = 155) and one in which rapid frozen sectioning was applied (n = 177). The associations with correct tumour annotation and clinicopathological variables, including age, pre-operative prostate specific antigen (PSA) levels, pathological Gleason score, pathological T stage, tumour volume and surgical margins, were examined using univariable and multivariable binary logistic regression models. RESULTS: For the gross visual inspection cohort the rate of correctly identifying and banking specimens containing prostate cancer was 69%. For the cohort assessed with rapid frozen sections, 94% of banked specimens actually had cancer. On multivariable analysis, we found that only frozen sectioning and tumour volume variables were independent predictors of correctly banked tumour specimens whilst all other routinely reported pathological variables had no influence on the success rates of fresh prostate tumour banking. CONCLUSION: The success rate for correctly banking fresh prostate tumour specimens is directly related to the tumour volume. Frozen section scrutiny of prostate samples is recommended to prevent misclassification of the banked material.

Prostate weight is the preferred measure of prostate size in radical prostatectomy cohorts.

OBJECTIVE: To evaluate the accuracy of calculated prostate volume variables in a radical prostatectomy (RP) cohort, as many recent studies use these measures of prostate size instead of prostate weight. To determine whether this accuracy could be improved by modifying the mathematical model used in the volume estimation. PATIENTS AND METHODS: Patients who underwent RP for prostate cancer at our associated institutions had calculated specimen volumes and weights from RP specimens determined at one pathology institution and transrectal ultrasonography (TRUS) volumes were recorded preoperatively (n= 236). Correlation analysis was performed and errors were determined for calculated volume variables when compared with prostate weight. Bland-Altman plots were drawn and concordance coefficients calculated. Analysis was repeated with smaller prostates mathematically modelled as bullet-shaped rather than ellipsoid (n= 165). RESULTS: Although correlation was good for both TRUS and specimen volumes, they equally underestimated prostate weight with a large range of errors and poor concordance coefficients. Only 22% of TRUS volumes and 11% of calculated specimen volumes were within 10% of weight measurements. Application of a bullet-shaped mathematical model for prostates <55 g did not correct the large individual variation seen within these values. CONCLUSION: Calculated prostate volume variables are prone to a large range of individual error regardless of the mathematical model used and should be avoided in statistical studies involving RP cohorts, and the more accurate prostate weight variable should instead be used as a size variable or correction factor.

Positive surgical margins are a risk factor for significant biochemical recurrence only in intermediate-risk disease.

UNLABELLED: What's known on the subject? and What does the study add? Positive surgical margins (PSMs) after radical prostatectomy are common, although their impact on the risk of disease recurrence is unknown. We examined the impact of PSMs on the risk of 'significant' biochemical recurrence stratified by their risk of occult metastatic disease. We find that only in intermediate-risk disease does the presence of a PSM have a significant impact on the risk of recurrence, and this represents a failure of technique. By contrast, for high- and low-risk disease, the risk of recurrence is driven by intrinsic tumour biology, and the presence of a PSM has little impact on outcome. OBJECTIVE: To determine the impact of surgical margin status on the risk of significant biochemical recurrence (prostate-specific antigen [PSA] doubling time <3, <6 or <9 months) after prostatectomy. MATERIALS AND METHODS: Patients undergoing radical prostatectomy with complete clinical and pathological data and detailed PSA follow-up were identified from two prospectively recorded databases. Patients were stratified according to their risk of occult systemic disease (low risk: PSA < 10 ng/dL, pT2 stage and Gleason score ≤6; intermediate risk: PSA 10-20 ng/dL, pT2 stage and/or Gleason score 7; high: PSA > 20 ng/dL or pT3-4 stage or Gleason score 8-10) and the impact of a positive surgical margin (PSM) within each stratum determined by univariable and multivariable analysis. RESULTS: Of 1514 patients identified, 276 (18.2%), 761 (50.3%) and 477 (31.5%) were classified as having low-, intermediate- and high-risk disease respectively. A total of 370 (24.4%) patients had a PSM and with a median follow-up of 22.2 months, and 165 (7%) patients had a biochemical recurrence. Sufficient PSA data was available to calculate PSA doubling times in 151/165 patients (91.5%). The PSM rate rose significantly, from 11% in low-risk to 43% in high-risk disease (P < 0.001), with similar positive associations noted with tumour grade, stage and serum PSA (P < 0.001). Patients with low-risk disease had essentially identical risks of significant biochemical recurrence over the study period, regardless of surgical margin status. By contrast, in patients with both intermediate- and high-risk disease, a PSM was a strong predictor of significant biochemical recurrence on univariable analysis. On multivariable analysis, howver, PSM predicted significant disease recurrence in intermediate-risk disease only. CONCLUSIONS: PSM is a risk factor for significant biochemical recurrence only in intermediate risk disease.