Stage pT0 in Radical Prostatectomy with No Residual Carcinoma and with a Previous Positive Biopsy Conveys a Wrong Message to Clinicians and Patients: Why Is Cancer Not Present in the Radical Prostatectomy Specimen?

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.

DNA comparison between operative and biopsy specimens to investigate stage pT0 after radical prostatectomy

PURPOSE

The aim was to eliminate, by DNA comparison, any identity mismatch between operative and biopsy specimens and to analyse the determinants of all pT0 prostate cancers occurred in a single institution.

METHODS

All prostate pT0 cases in a single institution over 20 years were investigated. None of the patients had been diagnosed after a transurethral resection of the prostate nor had they received neoadjuvant hormonal treatment. The biopsies performed in other centres had been referred for a centralized pathologic re-analysis. DNA analysis was performed in samples from operative and biopsy specimens, and pairs of tissues were blindly constituted. Correct matching was verified in each pair and compared to the original database in order to comment on the occurrence of identity mismatches in the series.

RESULTS

Nineteen patients (0.77 %) had been diagnosed as having pT0 prostate cancer among the 2,462 RP procedures performed over 19 years. The biopsy re-analysis invalidated the initial diagnosis of prostate cancer in one biopsy set performed elsewhere. Among 12 entirely processed cases, the biochemistry procedure evaluated as "very unlikely" the occurrence of an error in tissue identification in the biopsy setting, during the surgical procedure or the pathological analysis. No identification error of tissue samples was established in this first verified pT0 series.

CONCLUSIONS

Although it must be suspected, specimen identification error was not a cause for pT0 prostate cancer. Only after a full pathological and DNA verification, the pT0 stage remains a sole entity, unexplained in most cases.

Handling of radical prostatectomy specimens: total embedding with large-format histology

A problem when handling radical prostatectomy specimens (RPS) is that cancer is often not visible at gross examination, and the tumor extent is always underestimated by the naked eye. The challenge is increased further by the fact that prostate cancer is a notoriously multifocal and heterogeneous tumor. For the pathologist, the safest method to avoid undersampling of cancer is evidently that the entire prostate is submitted. Even though whole mounts of sections from RPS appear not to be superior to sections from standard blocks in detecting adverse pathological features, their use has the great advantage of displaying the architecture of the prostate and the identification and location of tumour nodules more clearly, with particular reference to the index tumour; further, it is easier to compare the pathological findings with those obtained from digital rectal examination (DRE), transrectal ultrasound (TRUS), and prostate biopsies. We are in favour of complete sampling of the RPS examined with the whole mount technique. There are reasons in favour and a few drawbacks. Its implementation does not require an additional amount of work from the technicians' side. It gives further clinical significance to our work of uropathologists.

International Society of Urological Pathology (ISUP) Consensus Conference on Handling and Staging of Radical Prostatectomy Specimens. Working group 1: specimen handling

The 2009 International Society of Urological Pathology Consensus Conference in Boston made recommendations regarding the standardization of pathology reporting of radical prostatectomy specimens. Issues relating to the handling and processing of radical prostatectomy specimens were coordinated by working group 1. Most uropathologists followed similar procedures for fixation of radical prostatectomy specimens, with 51% of respondents transporting tissue in formalin. There was also consensus that the prostate weight without the seminal vesicles should be recorded. There was consensus that the surface of the prostate should be painted. It was agreed that both the prostate apex and base should be examined by the cone method with sagittal sectioning of the tissue sample. There was consensus that the gland should be fully fixed before sectioning. Both partial and complete embedding of prostates was considered to be acceptable as long as the method of partial embedding is stated. No consensus was determined regarding the necessity of weighing and measuring the length of the seminal vesicles, the preparation of whole mounts rather than standardized blocks and the methodology for sampling of fresh tissue for research purposes, and it was agreed that these should be left to the discretion of the working pathologist.

Preoperative Clinical and Pathological Characteristics of pT0 Prostate Cancer in Radical Prostatectomy

Purpose

To analyze the preoperative clinical and pathological characteristics of patients with pT0 prostate cancer.

Materials and Methods

We retrospectively reviewed the records of 702 patients who underwent radical prostatectomy (RP) at our institution between January 2004 and July 2008 for clinically localized prostate cancer. If there was no evidence of residual tumor in the pathological specimen of the prostate, a patient was staged as pT0. Patients with pT0 disease were compared with a control group of patients who were operated on during the same period.

Results

Overall, 9 (1.3%) patients were staged as pT0 on the pathologic examination. Significant differences were observed between the pT0 group and the control patients in the biopsy Gleason score (p=0.004), the number of positive cores on biopsy (p=0.018), the tumor length of positive cores (p<0.001), and prostate volume (p=0.015). Cutoff values predictive of pT0 tumor status were defined as a biopsy Gleason score sum ≤6, 2 or fewer positive biopsy cores, tumor length on biopsy ≤2 mm, and prostate volume >30 cm³. Whereas 8 of the 9 (88.9%) pT0 patients showed all of these characteristics, only 55 of the 693 (7.9%) control patients fulfilled the criteria. The combination suggested above afforded a sensitivity of 88.8% and a specificity of 92.1% for the prediction of pT0 status.

Conclusions

The frequency of pT0 prostate cancer seen on RP was 1.3%. A combination of clinicopathological features, incorporating a biopsy Gleason score, the number of positive biopsy cores, tumor length on biopsy, and prostate volume, was useful to predict pT0 stage on RP.