Justin Peters

University of Melbourne, Melbourne, Victoria, Australia

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Publications (10)49.66 Total impact

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    ABSTRACT: Objective: To use nerve conduction studies to clarify the functional innervation of the male urethral rhabdosphincter. In particular, to test the hypothesis that in some men, fibres of the neurovascular bundle supply the rhabdosphincter. These fibres may be at risk during radical prostatectomy. Materials and methods: Men undergoing robot assisted radical prostatectomy for clinically localized prostate cancer were included. Men with a history of pelvic surgery/radiation/trauma, obesity or neurological diseases were excluded. Nerve conduction studies were performed before and after prostate removal. The St Mark's pudendal electrode was used for pudendal (control) stimulation. The ProPep Nerve-Monitoring System™(ProPep Surgical, Austin, Tx), was used to stimulate the neurovascular bundle at the level of the prostate base, mid and apex. ProPep® needle electrodes inserted into the rhabdosphincter were used to measure evoked compound motor action potential response. Results were only included if a valid pudendal control was elicited. Results: Seventeen men in total underwent investigation. Valid measurements were obtained after initial quality control in seven. In two cases, evidence of sphincteric activation was observed, providing evidence to support neurovascular bundle innervation of the rhabdosphincter. In the other five patients, no intrapelvic nerve supply was demonstrated. Conclusion: Somatic nerve supply to the rhabdosphincter is variable. Direct intrapelvic supply to the rhabdosphincter may exist in some men. This may be one explanation as to why some patients unexpectedly develop severe urinary incontinence post-operatively despite technically satisfactory surgery.
    No preview · Article · Oct 2015 · Urology
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    Full-text · Article · Apr 2015 · European Urology Supplements

  • No preview · Conference Paper · Mar 2015
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    ABSTRACT: Although the development of metastases correlates closely with depth of invasion in many tumor types, it is unclear if invasion into, but not through, the prostatic pseudocapsule has a negative impact on prognosis similar to extraprostatic extension (EPE). We aimed to define the impact of pseudocapsular invasion (PCI) on the risk of post-prostatectomy biochemical recurrence (BCR). Patients with pT2-3a prostate cancer were identified from a prospectively recorded database. Patients with pT2 disease were categorized according to the presence or absence of PCI. The impact of PCI on BCR was determined by univariable and multivariable Cox regression analysis. From a cohort of 1338, we identified 595 patients with organ-confined cancer positive for PCI. Compared to tumors without evidence of PCI, the presence of PCI was positively associated with tumors of higher Gleason grade (p<0.001) and tumor volume (1.2 vs. 1.9 cc, p<0.001). On univariable analysis, there was no difference in BCR-free survival between patients with or without PCI, although patients with EPE had a significantly lower BCR-free survival (p<0.001). This was confirmed on multivariable analysis, where EPE was a significant independent predictor of BCR (HR 1.53, p=0.018), whereas the presence of PCI had no effect (HR 0.81, p=0.33). PCI is not a pathological feature associated with an adverse outcome post-prostatectomy. This indicates that depth of tumor invasion is not a continuum of risk, and access to the periprostatic adipose tissue is a more important determinant of disease behavior than the presence of an invasive phenotype.
    Full-text · Article · Jun 2013 · The Journal of urology
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    ABSTRACT: 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.
    No preview · Article · Jan 2013 · BJU International
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    ABSTRACT: •  To examine the impact of seminal vesicle invasion (SVI) in patients with locally advanced (pT3) prostate cancer on clinical outcome. •  To explore the clinical association of SVI with metastatic disease. •  To distinguish between the possibilities that either seminal vesicles possess their own biological significance and represent a privileged staging site for systemic tumour cell dissemination, or that their invasion is a surrogate marker for an aggressive large-volume poorly differentiated cancer. •  Patients with extraprostatic extension (EPE) and/or SVI were identified from a prospectively recorded and maintained prostate cancer database. •  Patients were categorised according to the presence of SVI as determined by routine pathological assessment. Tumour volumes were measured routinely by computed planimetry at the time of histological assessment. •  The impact of SVI on biochemical recurrence with a definition of a prostate-specific antigen (PSA) level of ≥0.2 ng/mL, as well as a clinically significant recurrence defined as failure with a PSA doubling time of <6 months, was determined by univariable and multivariable Cox regression analysis. •  Of 249 patients with pT3 disease, 46 (18%) had SVI, 40 (87%) by direct extension and six (13%) metastatic. •  Tumours with SVI had significantly greater tumour burden as determined by total tumour volume (7.2 vs 3.7 mL, P < 0.001), index tumour volume (6.8 vs. 3.4 mL, P < 0.001) and percentage tumour volume (21.8 vs 12.4 %, P= 0.001). •  After controlling for tumour volume and Gleason score, the presence of SVI did not significantly predict for the development of a significant PSA recurrence. •  Our results suggest that SVI is a surrogate marker of larger and more aggressive tumours with higher Gleason scores rather than a privileged site of tumour cell dissemination.
    Full-text · Article · Dec 2012 · BJU International
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    ABSTRACT: Study Type – Therapy (case series) Level of Evidence 4 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.
    Full-text · Article · Jan 2012 · BJU International
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    ABSTRACT: Study Type – Diagnostic (exploratory cohort) Level of Evidence 2b What's known on the subject? and What does the study add? Due to sampling error, the Gleason score of clinically localized prostate cancer is frequently underestimated at the time of initial biopsy. Given that this may lead to inappropriate surveillance of patients with high-risk disease, there is considerable interest in identifying predictors of significant undergrading. Recently PSAD has been proposed to be an accurate predictor of subsequent upgrading in patients diagnosed with Gleason 6 disease on biopsy. We examined the predictive characteristics of PSAD in patients with low- and intermediate-risk disease on biopsy subsequently treated with radical prostatectomy. We found that although PSAD was a significant predictor of upgrade of biopsy Gleason 6 and 3 + 4 = 7 tumours, it failed to predict upgrading in patients with Gleason 7 tumours taken as a whole. When we explored reasons for this discrepancy, we found that the amount of PSA produced per unit tumour volume decreased with increasing Gleason score, thereby diminishing the predictive value of PSAD.
    No preview · Article · Nov 2011 · BJU International
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    ABSTRACT: • To determine the influence of tumour and prostate gland volumes on the underestimation of prostate cancer Gleason score in diagnostic core biopsies. • Patients undergoing radical prostatectomy with matched diagnostic biopsies were identified from a prospectively recorded database. • Tumour volumes were measured in serial whole-mount sections with image analysis software as part of routine histological assessment. • Differences in various metrics of tumour and prostate volume between upgraded tumours and tumours concordant for the lower or higher grade were analysed. • In all, 684 consecutive patients with Gleason score 6 or 7 prostate cancer on diagnostic biopsy were identified. • Of 298 patients diagnosed with Gleason 6 tumour on biopsy, 201 (67.4%) were upgraded to Gleason 7 or higher on final pathology. Similarly, of 262 patients diagnosed with Gleason 3 + 4 = 7 prostate cancer on initial biopsy, 60 (22.9%) were upgraded to Gleason score 4 + 3 = 7 or higher. • Tumours upgraded from Gleason 6 to 7 had a significantly lower index tumour volume (1.73 vs 2 mL, P= 0.029), higher calculated prostate volume (41.6 vs 39 mL, P= 0.017) and lower relative percentage of tumour to benign glandular tissue (4.3% vs 5.9%, P= 0.001) than tumours concordant for the higher grade. • Similarly, tumours that were Gleason score 3 + 4 on biopsy and upgraded on final pathology to 4 + 3 were significantly smaller as measured by both total tumour volume (2.3 vs 3.3 mL, P= 0.005) and index tumour volume (2.2 vs 3, P= 0.027) and occupied a smaller percentage of the gland volume (6.3% vs 8.9%, P= 0.017) compared with tumours concordant for the higher grade. • On multivariate analysis, lower prostate weight (hazard ratio 0.97, 95% confidence interval 0.96-0.99, P < 0.001) and larger total tumour volume (hazard ratio 1.87, 95% confidence interval 1.4-2.6, P < 0.001) independently predicted an upgrade in Gleason score from 6 to 7. In tumours upgraded from biopsy Gleason 3 + 4, only higher index tumour volume (hazard ratio 3.1, 95% confidence interval 1.01-9.3, P= 0.048) was a significant predictor of upgrading on multivariate analysis. • Under-graded tumours are significantly smaller than tumours concordant for the higher grade, indicating that incomplete tumour sampling plays a significant role in Gleason score assignment error. • Surrogate measures of tumour volume may predict those at greatest risk of Gleason score upgrade.
    No preview · Article · Sep 2011 · BJU International
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    ABSTRACT: •To determine the effect of an upgrade in Gleason score between initial prostate biopsy and final prostatectomy specimen on the risk of postoperative biochemical recurrence. •A total of 1629 patients with paired biopsy and radical prostatectomy histology were identified from two prospectively recorded prostate cancer databases. •Information on key clinical and pathological characteristics as well as prostate-specific antigen follow-up was recorded. •Patients who experienced an upgrade in their Gleason score were compared with corresponding patients with concordant tumours of the lower and higher grade. •Kaplan-Meier curves and multivariate models were generated to examine the impact of Gleason score upgrade on the risk of postoperative biochemical recurrence. •Overall, 466 patients (28.6%) experienced an upgrade in their Gleason score post radical prostatectomy, in 88.4% of cases involving a change in a single Gleason score point. •Patients upgraded from Gleason 6 (3 + 3) to Gleason 7 (3 + 4) had pathological characteristics that were very similar to Gleason 7 (3 + 4) concordant tumours, with an identical risk of biochemical recurrence. In contrast, patients upgraded from Gleason score 6 (3 + 3) to Gleason 7 (4 + 3) had tumours with pathological characteristics intermediate between the two concordant groups, which was mirrored by their risk of biochemical recurrence. •Patients with Gleason 7 tumours who experienced a change in the predominant pattern from 3 + 4 to 4 + 3 had tumours that resembled Gleason 7 (4 + 3) concordant tumours, with a similar risk of biochemical recurrence. In contrast, patients upgraded from Gleason 7 to Gleason >7 had tumours with intermediate pathological characteristics, and a risk of biochemical recurrence that was significantly different to concordant tumours of the lower and higher grade. •In multivariate models, a change in Gleason score was an independent predictor of biochemical recurrence in the preoperative setting only. •Although a difference in Gleason score was an independent predictor of recurrence in concordant tumours in models based on postoperative variables, an upgrade in Gleason score in discordant tumours was not, with differences in co-segregated adverse pathological characteristics being more predictive. •Patients experiencing an upgrade in their Gleason score between biopsy and final specimen exhibit significantly more aggressive pathological features than corresponding concordant tumours, and a higher risk of biochemical recurrence post radical prostatectomy. •As Gleason score can be more accurately assessed preoperatively than other prognostic tumour features, continued effort is required to identify those most at risk of upgrading, and to refine biopsy strategies to reduce sampling error.
    Full-text · Article · Mar 2011 · BJU International

Publication Stats

99 Citations
49.66 Total Impact Points

Institutions

  • 2011-2015
    • University of Melbourne
      • Department of Surgery
      Melbourne, Victoria, Australia
  • 2011-2013
    • Royal Melbourne Hospital
      • Department of Radiology
      Melbourne, Victoria, Australia