Justin Peters

Royal Melbourne Hospital, Melbourne, Victoria, Australia

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Publications (7)22.29 Total impact

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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.
    The Journal of urology 06/2013; · 4.02 Impact Factor
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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.
    BJU International 01/2013; · 3.05 Impact Factor
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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.
    BJU International 12/2012; 110 Suppl 4:58-63. · 3.05 Impact Factor
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    ABSTRACT: 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. 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. 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. 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. PSM is a risk factor for significant biochemical recurrence only in intermediate risk disease.
    BJU International 01/2012; 110(6):821-7. · 3.05 Impact Factor
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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. To analyse the performance of PSA density (PSAD) as a predictor of Gleason score upgrade in a large cohort stratified by Gleason score. We and others have shown that an upgrade in Gleason score between initial prostate biopsy and final radical prostatectomy (RP) pathology is a significant risk factor for recurrence after local therapy. Patients undergoing RP with matching biopsy information were identified from two prospective databases. Patients were analysed according to the concordance between biopsy and final pathology Gleason score in three paired groups: 6/>6, 3 + 4/>3 + 4, 7/>7. Receiver-operating characteristic (ROC) curves were generated stratified by Gleason score, and the area under the curve (AUC) calculated. Logistic regression models were fitted to identify significant predictors of tumour upgrade. From 1516 patients, 435 (29%) had an upgrade in Gleason score. ROC analysis showed a decline in AUC with increasing biopsy Gleason score, from 0.64 for biopsy Gleason score 6, to 0.57 for Gleason score 7. In logistic regression models containing pretreatment variables, e.g. clinical stage and number of positive cores, for Gleason score 6 and 3 + 4, PSAD was the strongest predictor of subsequent tumour upgrade (odds ratio [OR] 1.46, 95% confidence interval [95% CI] 1.18-1.83, P= 0.001 and OR 1.37, 95% CI 1.14-1.67, P= 0.002, respectively). Surprisingly, in tumours upgraded from Gleason score 7 to >7, PSAD was not predictive even on univariable analysis, whereas clinical stage and number of positive cores were significant independent predictors. To explore the relationship between serum PSA and Gleason score, tumour volume was calculated in 669 patients. There was a strong association between Gleason score and tumour volume, with the median volume of Gleason score 7 and Gleason score >7 tumours being approximately twice and four-times that of Gleason score 6 tumours, respectively (P < 0.001). In contrast, the median serum PSA level per millilitre tumour volume decreased significantly with increasing grade, from 5.4 ng/mL for Gleason score 6 to 2.1 ng/mL for >7 (P < 0.001). There is a strong correlation between Gleason score and tumour volume in well/intermediate differentiated tumours, and as they produce relatively high amounts of PSA per unit volume of cancer, high PSAD is the strongest single predictor of tumour undergrading. However, as higher grade tumours produce less PSA per unit volume, PSAD loses its predictive ability, and other clinical markers of tumour volume such as palpable disease and numbers of positive cores become more predictive.
    BJU International 11/2011; 110(1):36-42. · 3.05 Impact Factor
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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.
    BJU International 09/2011; 109(5):660-4. · 3.05 Impact Factor
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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.
    BJU International 03/2011; 108(8b):E202 - E210. · 3.05 Impact Factor