Comparative Analysis of Whole Mount Processing and Systematic Sampling of Radical Prostatectomy Specimens: Pathological Outcomes and Risk of Biochemical Recurrence

Added Clinical Value of Whole-mount Histopathology of Radical Prostatectomy Specimens: A Collaborative Review

CONTEXT

Whole-mount histopathology, that is, large format histology or whole-mount sectioning, refers to the histopathological examination of tissue sections from specimens processed with large tissue cassette. In some institutions, it is applied routinely to specimens with genitourinary cancers.

OBJECTIVE

To give an overview of the application of the large format histology to the morphological examination of the radical prostatectomy (RP) specimens.

EVIDENCE ACQUISITION

A comprehensive PubMed search was performed up to May 2020, using the keywords "prostate carcinoma," "radical prostatectomy specimens," "whole-mount histopathology," "whole mount sectioning," "large format histology," "macrosectioning," "diagnostic criteria," and "prognosis." The search, supplemented with a hand search, was restricted to articles published in the English language. No limitations were placed on the publication year. References in relevant articles were also reviewed.

EVIDENCE SYNTHESIS

Even though the whole-mount sections of RPs appear not to be superior to regular sections in detecting adverse pathological features, their use has the advantage of displaying the architecture of the prostate gland and identifying and locating tumor nodule(s) more clearly, with particular reference to the index tumor. Further, it is easier to compare the pathological features with clinical findings derived, for instance, from digital rectal examination, transrectal ultrasound, multiparametric magnetic resonance imaging, surgical operation, and prostate biopsies.

CONCLUSIONS

Urologists, radiologists, and oncologists are updated about the step forward made by pathologists when diagnostic and prognostic information is derived from an approach that closely resembles that used by the clinicians when dealing with imaging findings.

PATIENT SUMMARY

Adoption of the whole-mount histopathology adds clinical value in correlation with clinical/imaging findings of radical prostatectomy specimens.

Prostate cancer detection using combined auto-fluorescence and light reflectance spectroscopy: ex vivo study of human prostates

This study was conducted to evaluate the capability of detecting prostate cancer (PCa) using auto-fluorescence lifetime spectroscopy (AFLS) and light reflectance spectroscopy (LRS). AFLS used excitation at 447 nm with four emission wavelengths (532, 562, 632, and 684 nm), where their lifetimes and weights were analyzed using a double exponent model. LRS was measured between 500 and 840 nm and analyzed by a quantitative model to determine hemoglobin concentrations and light scattering. Both AFLS and LRS were taken on n = 724 distinct locations from both prostate capsular (nc = 185) and parenchymal (np = 539) tissues, including PCa tissue, benign peripheral zone tissue and benign prostatic hyperplasia (BPH), of fresh ex vivo radical prostatectomy specimens from 37 patients with high volume, intermediate-to-high-grade PCa (Gleason score, GS ≥7). AFLS and LRS parameters from parenchymal tissues were analyzed for statistical testing and classification. A feature selection algorithm based on multinomial logistic regression was implemented to identify critical parameters in order to classify high-grade PCa tissue. The regression model was in turn used to classify PCa tissue at the individual aggressive level of GS = 7,8,9. Receiver operating characteristic curves were generated and used to determine classification accuracy for each tissue type. We show that our dual-modal technique resulted in accuracies of 87.9%, 90.1%, and 85.1% for PCa classification at GS = 7, 8, 9 within parenchymal tissues, and up to 91.1%, 91.9%, and 94.3% if capsular tissues were included for detection. Possible biochemical and physiological mechanisms causing signal differences in AFLS and LRS between PCa and benign tissues were also discussed.

Whole-mount evaluation of penectomies for penile cancer: feasibility, cost and comparison to routine sectioning

AIMS

Pathological staging in penectomies may be difficult due to the anatomical complexity of penile anatomy, and may be additionally challenging due to the low volume at most institutions. Our study aimed to assess the feasibility of whole-mount processing for penectomy specimens.

METHODS AND RESULTS

A 7-year retrospective search for partial or radical penectomies identified 55 specimens, which were processed routinely (n = 31) from 2006 to 2009 and whole-mounted (n = 24) from 2010 to 2012. Routine cases used more slides per case compared to whole mounts (mean 10.4 versus 7.2). Recuts occurred more often in routine cases (12.9% versus 0%). More routine cases had additional blocks grossed (19.4% versus 4.2%). Upon review, five discrepancies that impacted pT staging were identified in the routine group, with none in the whole-mount group. The average estimated additional cost for each whole-mount case compared to routine processing was $40.74, with an increased turnaround time of 1 day.

CONCLUSIONS

Whole-mounting is a feasible technique for penectomy that can be utilized with minimal increased cost and turnaround time, and may improve staging. Institutions in which whole-mounting is already established for other organs, such as prostate, may wish to consider utilizing this format for penectomy specimens.

Partial sampling of radical prostatectomy specimens: detection of positive margins and extraprostatic extension

Currently there is no global agreement as to how extensively a radical prostatectomy specimen should be sectioned and histologically examined. We analyzed the ability of different methods of partial sampling in detecting positive margin (PM) and extraprostatic extension (EPE)-2 pathologic features of prostate cancer that are most easily missed by partial sampling of the prostate. Radical prostatectomy specimens from 617 patients treated with open radical prostatectomy between 1992 and 2011 were analyzed. Examination of the entirely submitted prostate detected only PM in 370 (60%), only EPE in 100 (16%), and both in 147 (24%) specimens. We determined whether these pathologic features would have been diagnosed had the examination of the specimen been limited only to alternate sections (method 1), alternate sections representing the posterior aspect of the gland in addition to one of the mid-anterior aspects (method 2), and every section representing the posterior aspect of the gland in addition to one of the mid-anterior aspects, supplemented by the remaining ipsilateral anterior sections if a sizeable tumor is seen (method 3). Methods 1 and 2 missed 13% and 21% of PMs and 28% and 47% of EPEs, respectively. Method 3 demonstrated better results missing only 5% of PMs and 7% of EPEs. Partial sampling techniques missed slightly more PMs and EPEs in patients with low-risk to intermediate-risk prostate cancer, although even in high-risk cases none of the methods detected all of the studied aggressive pathologic features.

Correlation of histomorphologic findings and partial neurovascular bundle preservation during laparoscopic and robotic radical prostatectomy

The objective of this work was to compare the amount of residual periprostatic tissue for radical prostatectomy performed by the partial NS (PNS) technique with that performed by the nerve-sparing (NS) or wide-resection (WR) techniques. Retrospective histomorphologic evaluation of radical prostatectomy specimens (RPSs) from patients undergoing laparoscopic radical prostatectomy (LRP) or robot-assisted radical prostatectomy (RARP) was performed. The posterolateral regions corresponding to the neurovascular bundle in RPSs from 48 patients who had undergone NS, PNS, or WR during LRP (n = 30) or RARP (n = 18) were examined by two pathologists unaware of the technique used. The RPSs were evaluated at the base, mid-gland, and apex. The amount of periprostatic tissue at each site was recorded. Measurements were analyzed by use of a linear mixed model. For both LRP and RARP, each gradation of nerve-preservation was associated with periprostatic tissue, except PNS and WR did not differ for LRP at the apex and base or for RARP at the apex, mid-gland, and base. For LRP, a greater amount of tissue was on the left side of the prostate than on the right at the mid-gland level (P = 0.004) whereas for RARP the opposite was found (P = 0.024). Of 18 separate analyses, 13 were significantly associated. The study is limited by its retrospective design. The amount of periprostatic tissue in the neurovascular bundle area correlates well with the nerve-preservation approach used during LRP and RARP, providing anatomic evidence supporting the PNS approach. We also describe a novel finding of laterality bias at the mid-gland level in LRP and RARP specimens.

Prostate cancer: multiparametric MRI for index lesion localization--a multiple-reader study

OBJECTIVE

The purpose of this study was to evaluate the utility of multiparametric MRI in localization of the index lesion of prostate cancer.

MATERIALS AND METHODS

Fifty-one patients who underwent 3-T MRI of the prostate with a pelvic phased-array coil that included T2-weighted, diffusion-weighted, and dynamic contrast-enhanced sequences before prostatectomy were included. Six radiologists assessed all images to identify the lesion most suspicious of being the index lesion, which was localized to one of 18 regions. A uropathologist using the same 18-region scheme reviewed the prostatectomy slides to localize the index lesion. MRI performance was assessed by requiring either an exact match or an approximate match (discrepancy of up to one region) between the MRI and pathologic findings in terms of assigned region.

RESULTS

The pathologist identified an index lesion in 49 of 51 patients. In exact-match analysis, the average sensitivity was 60.2% (range, 51.0-63.3%), and the average positive predictive value (PPV) was 65.3% (range, 61.2-69.4%). In approximate-match analysis, the average sensitivity was 75.9% (range, 65.3-69.6%), and the average PPV was 82.6% (range, 79.2-91.4%). The sensitivity was higher for index lesions with a Gleason score greater than 6 in exact-match (74.8% vs 15.3%, p<0.001) and approximate-match (88.7% vs 36.1%, p=<0.001) analyses and for index lesions measuring at least 1 cm in approximate-match analysis (80.3% vs 58.3%, p=0.016). In exact-match analysis, 30.0%, 44.9%, and 79.1% of abnormalities found with one, two, and three MRI parameters represented the index lesion (p<0.001).

CONCLUSION

The sensitivity and PPV of multiparametric MRI for index lesion localization were moderate, although they improved in the setting of more aggressive pathologic features and a greater number of abnormal MRI parameters, respectively.

Next-generation prostate cancer biobanking: toward a processing protocol amenable for the International Cancer Genome Consortium

Next-generation DNA and RNA sequencing requires intact nucleic acids from high-quality human tissue samples to better elucidate the molecular basis of cancer. We have developed a prostate biobanking protocol to acquire suitable samples for sequencing without compromising the accuracy of clinical diagnosis. To assess the clinical implications of implementing this protocol, we evaluated 105 consecutive radical prostatectomy specimens from November 2008 to February 2009. Alternating levels of prostate samples were submitted to Surgical Pathology as formalin-fixed, paraffin-embedded blocks and to the institutional biobank as frozen blocks. Differences in reported pathologic characteristics between clinical and procured specimens were compared. Clinical staging and grading were not affected by the biobank protocol. Tumor foci on frozen hematoxylin and eosin slides were identified and high-density tumor foci were scored and processed for DNA and RNA extractions for sequencing. Both DNA and RNA were extracted from 22 cases of 44 with high-density tumor foci. Eighty-two percent (18/22) of the samples passed rigorous quality control steps for DNA and RNA sequencing. To date, DNA extracted from 7 cases has undergone whole-genome sequencing, and RNA from 18 cases has been RNA sequenced. This protocol provides prostate tissue for high-throughput biomedical research and confirms the feasibility of actively integrating prostate cancer into The Cancer Genome Atlas Program, a member of the International Cancer Genome Consortium.

Prostate size as a predictor of Gleason score upgrading in patients with low risk prostate cancer

PURPOSE

Gleason score upgrading between biopsy and surgical pathological specimens occurs in 30% to 50% of cases. Predicting upgrading in men with low risk prostate cancer may be particularly important since high grade disease influences management decisions and impacts prognosis. We determined whether prostate size predicts Gleason score upgrading in patients with low risk prostate cancer.

MATERIALS AND METHODS

A total of 1,251 consecutive patients with D'Amico low risk disease and complete data available underwent radical prostatectomy at our institution between January 2000 and June 2008. Patients were divided into 3 groups by pathological Gleason score, including no, minor (3 + 4 = 7) and major (4 + 3 = 7 or greater) Gleason score upgrading. We developed bivariate and multivariate models to determine whether prostate size was an important predictor of upgrading while controlling for clinical and biopsy characteristics.

RESULTS

Of 1,251 cases 387 (31.0%) were upgraded, including 324 (26%) and 63 (5%) with minor and major upgrading, respectively. As expected, Gleason score upgrading was associated with worse pathological and cancer control outcomes. On multivariate analysis smaller prostate size was an independent predictor of any and major upgrading (OR 0.58, 95% CI 0.48-0.69, p <0.01 and OR 0.67, 95% CI 0.49-0.96, p = 0.03, respectively). Men with prostate volume at the 25th percentile (36 cm(3)) were 50% more likely to experience upgrading than men with prostate volume at the 75th percentile (58 cm(3)).

CONCLUSIONS

Of low risk cases 31% were upgraded at final pathology. Smaller prostate size predicts Gleason score upgrading in men with clinically low risk prostate cancer. This is important information when counseling patients on management and prognosis.

Solitary and small (≤3 mm) apical positive surgical margins are related to biochemical recurrence after radical prostatectomy

OBJECTIVES

To evaluate the prognostic value of positive surgical margins (PSM) in radical prostatectomy (RPE) specimens in relation to multifocality, localization and size.

METHODS

A total of 1036 patients who underwent RPE and staged pT2-3a,pN0,M0 were evaluated. None had received adjuvant or neoadjuvant therapy. All specimens were routinely processed by complete whole mount sectioning. Exact number, localization and size of PSM were reassessed, and patients were followed up for a mean of 60 months.

RESULTS

A total of 267 patients (26%) showed PSM (20% pT2, 48% pT3a). Preoperative prostate-specific antigen, Gleason score (GS) and PSM were independent predictors of biochemical recurrence (BCR). BCR-free survival rates for patients with and without PSM were 59% and 80%, respectively (HR 2.1; P < 0.001). PSM were related to biochemical failure in pT2 and pT3a tumors (P = 0.001 and P = 0.015). A total of 64% of solitary PSM were apical. Multifocality, localization and size of PSM had no significant impact on BCR.

CONCLUSIONS

Solitary apical and small PSM in RPE have a significant impact on BCR-free survival in localized stages.