Prognosis of Mucinous Adenocarcinoma of the Prostate Treated by Radical Prostatectomy: A Study of 47 Cases

Morphologic patterns observed in prostate biopsy cases with discrepant grade group and molecular risk classification

BACKGROUND

Molecular-based risk classifier tests are increasingly being utilized by urologists and radiation oncologists to guide clinical decision making. The Decipher prostate biopsy test is a 22-gene RNA biomarker assay designed to predict likelihood of high-grade disease at radical prostatectomy and risk of metastasis and mortality. The test provides a risk category of low, intermediate, or high. We investigated histologic features of biopsies in which the Grade Group (GG) and Decipher risk category (molecular risk) were discrepant.

METHODS

Our institutional urologic outcomes database was searched for men who underwent prostate biopsies with subsequent Decipher testing from 2016 to 2020. We defined discrepant GG and molecular risk as either GG1-2 with high Decipher risk category or GG ≥ 3 with low Decipher risk category. The biopsy slide on which Decipher testing was performed was re-reviewed for GG and various histologic features, including % Gleason pattern 4, types of Gleason pattern 4 and 5, other "high risk" features (e.g., complex papillary, ductal carcinoma, intraductal carcinoma [IDC]), and other unusual and often "difficult to grade" patterns (e.g., atrophic carcinoma, mucin rupture, pseudohyperplastic carcinoma, collagenous fibroplasia, foamy gland carcinoma, carcinoma with basal cell marker expression, carcinoma with prominent vacuoles, and stromal reaction). Follow-up data was also obtained from the electronic medical record.

RESULTS

Of 178 men who underwent prostate biopsies and had Decipher testing performed, 41 (23%) had discrepant GG and molecular risk. Slides were available for review for 33/41 (80%). Of these 33 patients, 23 (70%) had GG1-2 (GG1 n = 5, GG2 n = 18) with high Decipher risk, and 10 (30%) had GG ≥ 3 with low Decipher risk. Of the 5 GG1 cases, one case was considered GG2 on re-review; no other high risk features were identified but each case showed at least one of the following "difficult to grade" patterns: 3 atrophic carcinoma, 1 collagenous fibroplasia, 1 carcinoma with mucin rupture, and 1 carcinoma with basal cell marker expression. Of the 18 GG2 high Decipher risk cases, 2 showed GG3 on re-review, 5 showed large cribriform and/or other high risk features, and 10 showed a "difficult to grade" pattern. Of the 10 GG ≥ 3 low Decipher risk cases, 5 had known high risk features including 2 with large cribriform, 1 with IDC, and 1 with Gleason pattern 5.

CONCLUSIONS

In GG1-2 high Decipher risk cases, difficult to grade patterns were frequently seen in the absence of other known high risk morphologic features; whether these constitute true high risk cases requires further study. In the GG ≥ 3 low Decipher risk cases, aggressive histologic patterns such as large cribriform and IDC were observed in half (50%) of cases; therefore, the molecular classifier may not capture all high risk histologic patterns.

Mucinous Adenocarcinoma of the Prostate With Normal Prostate-Specific Antigen Levels, Pulmonary Metastasis, and the Absence of Nodal Disease: A Case Report

A 74-year-old man was suffering from nine months of perineal pain and progressive worsening of urinary symptoms including nocturia and urgency. His prostate-specific antigen (PSA) levels were 1.48 ng/mL at the time of referral. Initially, a differential diagnosis of prostatitis or seminal vesicle inflammation was made, and four weeks of antibiotics were prescribed, which were later extended to six weeks due to failure of symptoms to resolve. Magnetic resonance imaging (MRI) of the prostate was then conducted. The impression was that there was ejaculatory duct obstruction caused by enlarged seminal vesicles with no evidence of significant prostate cancer. The prostate-specific antigen density (PSAd) was 0.04, and the prostate imaging reporting and data system (PIRADS) score was I-II. A CT chest with contrast was conducted for further investigation of pulmonary nodules found on the CT urogram. It revealed multiple calcified pulmonary nodules which were suspicious of malignancy. A CT-guided biopsy of one of the pulmonary nodules was taken, and histopathological analysis revealed a mucinous adenocarcinoma. A transurethral resection of the prostate (TURP) was then performed. Histopathological analysis of the prostatic surgical specimen revealed invasive mucinous adenocarcinoma. Based on the findings, a diagnosis of mucinous adenocarcinoma of the prostate with atypical lung metastasis without osseous or regional lymph node involvement was made, stage T4 N0 M1a. The patient is currently on a treatment regimen consisting of carboplatin, pemetrexed, and pembrolizumab.

The therapeutic efficacy of radical prostatectomy and external beam radiation therapy in patients with different pathological patterns of prostate cancer

BACKGROUND

We aim to investigate the prognostic value of different pathological patterns of non-adenocarcinoma prostate cancers (PCa) in radical prostatectomy (RP) and external beam radiation therapy (EBRT).

METHODS

Data of 470,258 localized PCa patients between 2004 and 2016 were collected from the Surveillance, Epidemiology, and End Results database. Propensity score matching was performed to balance the baseline characteristics of patients in different groups. Kaplan-Meier curves and Cox regression were used for survival analysis. Overall survival (OS) and cancer-specific survival (CSS) were set as endpoints.

RESULTS

Totally, 1044 patients with non-adenocarcinoma patterns of PCa were included. Patients with small cell neuroendocrine carcinoma (SCNC) and neuroendocrine differentiation (NED) harbored the worst prognosis in both RP and EBRT among all pathological groups. RP exhibited superior effects to EBRT for this group of cases. Ductal carcinoma (DA) was also related to poorer survival outcomes versus PAC in both local therapies. Yet, for men with DA, both RP and EBRT still improved patients' prognosis against no local therapy (NLT), with RP being the superior modality. Cases harboring mucinous adenocarcinoma (MA) and signet ring cell carcinoma (SRCC) shared comparable clinical outcomes to men with PAC. However, for cases with MA, neither RP nor EBRT was related to better survival outcomes against NLT, while for patients with SRCC, both RP and EBRT prolonged patients' survival with similar effects.

CONCLUSIONS

Our study provided a comprehensive view of the treatment effect of RP and EBRT in non-adenocarcinoma PCa patients. These findings could facilitate clinicians in making therapeutic decision-making for non-adenocarcinoma patients.

Left testicular and pulmonary metastases of mucinous adenocarcinoma of the prostate after robot-assisted radical prostatectomy

Introduction

We present a case of mucinous adenocarcinoma of the prostate with testicular and lung metastases following robot-assisted radical prostatectomy, androgen deprivation therapy, and radiotherapy.

Case presentation

A 73-year-old man with a prostate-specific antigen level of 4.3 ng/mL was diagnosed with prostate cancer. Following the robot-assisted radical prostatectomy, the pathological diagnosis was mucinous adenocarcinoma of the prostate (pT3bpN0, Gleason score of 4 + 4). Salvage hormonal therapy and irradiation were performed after the prostatectomy. Enlargement of the left testis was noted, and 28 months after prostatectomy, computed tomography detected a left testicular tumor and nodular lesions in the bilateral lungs. The histopathological diagnosis of left high orchiectomy was metastasis of a mucinous adenocarcinoma of the prostate. Chemotherapy with docetaxel followed by cabazitaxel was initiated.

Conclusion

Mucinous prostate adenocarcinoma with distal metastases following prostatectomy has been managed for longer than 3 years with multiple treatments.

Impact of Epithelial Histological Types, Subtypes, and Growth Patterns on Oncological Outcomes for Patients with Nonmetastatic Prostate Cancer Treated with Curative Intent: A Systematic Review

CONTEXT

The optimal management for men with prostate cancer (PCa) with unconventional histology (UH) is unknown. The outcome for these cancers might be worse than for conventional PCa and so different approaches may be needed.

OBJECTIVE

To compare oncological outcomes for conventional and UH PCa in men with localized disease treated with curative intent.

EVIDENCE ACQUISITION

A systematic review adhering to the Referred Reporting Items for Systematic Reviews and Meta-Analyses was prospectively registered on PROSPERO (CRD42022296013) was performed in July 2021.

EVIDENCE SYNTHESIS

We screened 3651 manuscripts and identified 46 eligible studies (reporting on 1 871 814 men with conventional PCa and 6929 men with 10 different PCa UHs). Extraprostatic extension and lymph node metastases, but not positive margin rates, were more common with UH PCa than with conventional tumors. PCa cases with cribriform pattern, intraductal carcinoma, or ductal adenocarcinoma had higher rates of biochemical recurrence and metastases after radical prostatectomy than for conventional PCa cases. Lower cancer-specific survival rates were observed for mixed cribriform/intraductal and cribriform PCa. By contrast, pathological findings and oncological outcomes for mucinous and prostatic intraepithelial neoplasia (PIN)-like PCa were similar to those for conventional PCa. Limitations of this review include low-quality studies, a risk of reporting bias, and a scarcity of studies that included radiotherapy.

CONCLUSIONS

Intraductal, cribriform, and ductal UHs may have worse oncological outcomes than for conventional and mucinous or PIN-like PCa. Alternative treatment approaches need to be evaluated in men with these cancers.

PATIENT SUMMARY

We reviewed the literature to explore whether prostate cancers with unconventional growth patterns behave differently to conventional prostate cancers. We found that some unconventional growth patterns have worse outcomes, so we need to investigate if they need different treatments. Urologists should be aware of these growth patterns and their clinical impact.

Prostate Cancer: Update on Grading and Reporting

The Gleason scoring system and Grade Group systems facilitate accurate grading and reporting of prostate cancer, which are essential tasks for surgical pathologists. Gleason Pattern 4 is critical to recognize because it signifies a risk for more aggressive behavior than Gleason Pattern 3 carcinoma. Prostatic adenocarcinoma with radiation or androgen therapy effect, with aberrant P63 expression, or with Paneth cell-like differentiation represent pitfalls in prostate cancer grading because although they display architecture associated with aggressive behavior in usual prostatic adenocarcinoma, they do not behave aggressively and using conventional Gleason scoring in these tumors would significantly overstate their biologic potential.

Mucin-producing urothelial-type adenocarcinoma of the prostate diagnosed after robot-assisted radical prostatectomy

INTRODUCTION

Mucin-producing adenocarcinoma of the prostate is a rare disease that includes prostate adenocarcinoma with mucus production, secondary adenocarcinoma from the bladder or colorectum, and adenocarcinoma from the urothelium of the prostatic urethra. We describe prostate-specific antigen-negative mucin-producing urothelial-type adenocarcinoma of the prostate.

CASE PRESENTATION

The patient had urinary retention and a serum prostate-specific antigen level of 0.74 ng/mL. Computed tomography and magnetic resonance imaging revealed a prostate tumor with a mucous component. We diagnosed adenocarcinoma by prostate biopsy and subsequently performed robot-assisted radical prostatectomy. Mucin-producing urothelial-type adenocarcinoma of the prostate was diagnosed by pathological examinations. Lung metastasis, developing within 3 months after surgery, was treated using chemotherapy.

CONCLUSION

Endocrine therapy is ineffective for mucin-producing urothelial-type adenocarcinoma of the prostate. Mucin-producing urothelial-type adenocarcinoma of the prostate diagnosis requires pathological and immunohistochemical analyses. It is important to surgically remove the primary lesion, and robot-assisted radical prostatectomy may provide an effective approach. Multimodal therapy is essential to treat for mucin-producing urothelial-type adenocarcinoma of the prostate.

Prostate adenocarcinoma with mucinous features - is it PSMA avid?

Mucinous prostate adenocarcinoma represents <0.1% of prostate cancers. To our knowledge, no previous report has described the ⁶⁸ Ga-PSMA-PET characteristics of this entity at the primary site. We present a case of a fit 85-year-old with PSA 0.55 ng/mL and ISUP grade 4 acinar adenocarcinoma with mucinous features on biopsy. ⁶⁸ Ga-PSMA-PET revealed an intensely avid primary lesion in the right prostate (SUVmax 10.9), concordant with biopsy findings and encompassing both the PI-RADS 5 lesion identified on MRI and a PI-RADS 1 lesion that presumably represented the mucinous component. The patient was treated with definitive radiotherapy to the prostate and lymph nodes with 6 months of androgen deprivation therapy.

ISUP Consensus Definition of Cribriform Pattern Prostate Cancer

The presence of a cribriform pattern is now recognized as a clinically important, independent adverse prognostic indicator for prostate cancer. For this reason the International Society of Urological Pathology (ISUP) recently recommended its inclusion in standard reporting. In order to improve interobserver agreement as to the diagnosis of cribriform patterns, the ISUP assembled an international panel of 12 expert urogenital pathologists for the purpose of drafting a consensus definition of cribriform pattern in prostate cancer, and provide their opinions on a set of 32 images and on potential diagnostic criteria. These images were selected by the 2 nonvoting convenors of the study and included the main categories where disagreement was anticipated. The Delphi method was applied to promote consensus among the 12 panelists in their review of the images during 2 initial rounds of the study. Following a virtual meeting, convened to discuss selected images and diagnostic criteria, the following definition for cribriform pattern in prostate cancer was approved: "A confluent sheet of contiguous malignant epithelial cells with multiple glandular lumina that are easily visible at low power (objective magnification ×10). There should be no intervening stroma or mucin separating individual or fused glandular structures" together with a set of explanatory notes. We believe this consensus definition to be practical and that it will facilitate reproducible recognition and reporting of this clinically important pattern commonly seen in prostate cancer. The images and the results of the final Delphi round are available at the ISUP website as an educational slide set (https://isupweb.org/isup/blog/slideshow/cribriform-slide-deck/).

Case Report: Mucinous Adenocarcinoma Arising From Congenital Ejaculatory Duct Cyst

Herein we present a previously unreported rare case of mucinous adenocarcinoma arising from a congenital ejaculatory duct cyst. Radiographic and endoscopic examinations revealed the tumor occurred in a cyst running through the prostate. Initially, the immunohistochemical pathology results showed that it was a metastatic mucinous adenocarcinoma, but no other primary lesions were clinically evidenced. Based on the embryonic development process of the male urogenital tract, the malformation of the patient's ejaculatory duct, and the pathological examination of the resected specimen, we considered the tumor to be a primary mucinous adenocarcinoma which originating from the hypoplastic ejaculatory duct. The tumor may have developed from the foci of intestinal metaplasia from cloacal remnants during embryonic development.

Cribriform prostate cancer: Morphologic criteria enabling a diagnosis, based on survey of experts

Among four sub-patterns of Gleason grade 4 prostate cancer, voluminous evidence supports that the cribriform pattern holds an unfavorable prognostic impact, as compared with poorly-formed, fused, or glomeruloid. The International Society of Urological Pathology (ISUP) recommends specifying whether invasive grade 4 cancer is cribriform. Recently, ISUP experts published a consensus definition of cribriform pattern highlighting criteria that distinguish it from mimickers. The current study aimed to analyze morphologic features separately to identify those that define the essence of the cribriform pattern. Thirty-two selected photomicrographs were classified by 12 urologic pathologists as: definitely cribriform cancer, probably cribriform, unsure, probably not cribriform, or definitely not cribriform. Consensus was defined as 9/12 agree or disagree, with ≤1 strongly supporting the opposite choice. Final consensus was achieved in 21 of 32 cases. Generalized estimating equation (GEE) model with logit link was fitted to estimate effect of multiple morphologic predictors. Fisher exact test was used for categorical findings. Presence of intervening stroma precluded calling cribriform cancer (p = 0.006). Mucin presence detracted (p = 0.003) from willingness to call cribriform cancer (only 3 cases had mucin). Lumen number was associated with cribriform consensus (p = 0.0006), and all consensus cases had ≥9 lumens. Predominant papillary pattern or an irregular outer boundary detracted (p = NS). Invasive cribriform carcinoma should have absence of intervening stroma, and usually neither papillary pattern, irregular outer boundary, nor very few lumens. Setting the criteria for cribriform will help prevent over- or undercalling this important finding.

Case Report: Prostate Adenocarcinoma With Mucinous Features of Normal-Level Serum PSA, Atypical Imaging, Biopsy-Negative, and Peculiar Urethrocystoscopic Manifestation

Background

Mucinous tumors of the prostate are seen as rare morphological variants of prostate carcinoma. Misdiagnosis and missed diagnosis are frequent clinically, especially when the clinical performance appears atypical. Furthermore, there has not been reported about the urethrocystoscopic performance of mucinous adenocarcinoma growing into the prostatic urethra so far.

Case Presentation

The current case report describes a 48-year old Asian male who was hospitalized because of intermittent gross hematuria for more than two months. The patient was diagnosed as prostatic space occupying lesions and an examination of needle biopsy was conducted on him, which did not indicate a definite malignancy. Transurethral plasma kinetic resection of the prostate (TUPKP) was performed for the patient, but the postoperative pathology revealed prostatic adenocarcinoma with mucinous features. Specifically, two cord-like neoplasms, extending to the bladder neck, were found through urethrocystoscopy in the prostatic urethra, both of which grew pedicles. The pedicles were situated on the right side of the parenchyma of the prostate. Finally, the patient underwent radical prostatectomy three weeks later.

Conclusion

Here, we reported a case that prostatic adenocarcinoma with mucinous features was diagnosed after TUPKP. The patient had normal serum prostate-specific antigen levels with atypical images and negative biopsy result. This report lays stress on the vigilance of clinicians in prostate mucinous adenocarcinoma and makes a description of its peculiar urethrocystoscopic manifestation, typical imaging, and unique growth pattern for the first time.

Uncommon Prostate Malignant Neoplasms

Prostate adenocarcinoma is the most common prostate cancer; however, there are several other malignant neoplasms that radiologists should be familiar with. The histological classification of malignant prostate neoplasms includes epithelial tumors, mesenchymal tumors, neuroendocrine tumors, hematolymphoid tumors, and stromal tumors. Knowledge of the main clinical and prostate magnetic resonance imaging features of uncommon tumors beyond adenocarcinoma is important for radiologists to enlarge their diagnostic ability and guide referring physician regarding the appropriate patient workup.The aim of this review article is to (1) review the main anatomical and histological concepts of the prostate gland and (2) provide an overview of uncommon prostate malignant neoplasms, emphasizing the key clinical, pathological, and imaging findings that may help radiologists in their daily interpretation of prostate magnetic resonance imaging.

Mucinous Prostate Cancer Shows Similar Prognosis to Typical Prostate Acinar Carcinoma: A Large Population-Based and Propensity Score-Matched Study

Background: Mucinous prostate cancer (PCa) is an extremely rare form of prostate malignancy. To date, the limited knowledge of its biology and outcomes stems from mostly small, single institution experiences. We analyzed the Surveillance, Epidemiology, and End Results (SEER) database to explore the incidence and treatment of mucinous PCa together with its prognostic factors to gain relatively large and consolidated insights. Methods: Age-adjusted incidence (AAI) rates were evaluated over time. Propensity score matching (PSM) and Kaplan-Meier analyses were used to compare the prognosis between mucinous PCa and typical prostate acinar adenocarcinoma. We assessed cancer-specific survival (CSS) and overall survival (OS) after patient stratification according to summary stage and treatment choice. Cox hazards regression analysis was performed to determine independent predictors of CSS and OS. Results: The AAI in 2016 was 0.24 per million. Patients with mucinous PCa had similar CSS and OS to matched individuals with typical prostate acinar adenocarcinoma. In terms of treatment, 65.3% of mucinous PCa patients underwent surgery, and 23.9% received radiation therapy. Patients who underwent surgery had longer survival (CSS, p = 0.012; OS, p < 0.001), and patients who received radiation therapy had similar survival to those who did not receive radiation therapy (CSS, p = 0.794; OS, p = 0.097). A multivariate Cox analysis for CSS and OS showed that older age (CSS: HR: 4.982, p = 0.001; OS: HR: 4.258, p < 0.001) and distant stage (CSS: HR: 40.224, p < 0.001; OS: HR: 9.866, p < 0.001) were independent prognostic factors for mucinous PCa patients. Conclusions: Mucinous PCa has an extremely low AAI. Analysis of its outcomes indicates that it is not a more malignant tumor as previously suspected. Mucinous PCa shows a similar prognosis to typical prostate acinar carcinoma. Surgery was associated with prolonged survival. An older age at diagnosis and distant stage was associated with poor survival.

Incidental discovery of mucinous adenocarcinoma of the prostate following transurethral resection of the prostate: A report of two cases and a literature review

Mucinous carcinoma is an unusual subtype of prostate cancer. In particular, mucinous adenocarcinomas identified following transurethral resection of the prostate (TURP) are extremely rare. The present study conducted are retrospective analysis of two cases of mucinous carcinoma of the prostate, which were incidentally diagnosed following histological examination of the specimens obtained by TURP. The pathological findings, treatment regimen and clinical course of the two cases were reviewed. One of the patients, whose surgical specimen stained positive for carcinoembryonic antigen (CEA) and negative for prostate-specific antigen (PSA), did not respond to androgen deprivation therapy (ADT). However, the other patient, whose specimen stained positive for PSA, was responsive to ADT, resulting in a better prognosis. Therefore, absence of PSA staining in surgical prostate specimens may be associated with a poor response to ADT and a worse prognosis.

Mucinous and secondary tumors of the prostate

Primary mucinous tumors and secondary tumors involving the prostate gland are relatively uncommon, however they have important diagnostic, therapeutic, and prognostic implications. The primary mucinous tumors of the prostate include mucinous (colloid) adenocarcinoma of the prostate, prostatic adenocarcinoma with mucinous features, and mucinous adenocarcinoma of the prostatic urethra (mucin-producing urothelial-type adenocarcinoma of the prostate). Mucinous adenocarcinoma of the prostate is defined as a primary prostatic acinar tumor characterized by the presence of at least 25% of the tumor composed of glands with extraluminal mucin. This diagnosis can only be made in radical prostatectomy specimens. Recent studies have shown that these tumors have a similar or in some cases better prognosis than conventional prostatic adenocarcinoma treated by radical prostatectomy. The preferred terminology for tumors that are composed of <25% extraluminal mucinous component in radical prostatectomy specimens is 'prostatic adenocarcinoma with mucinous features.' All cases of prostatic adenocarcinoma with extraluminal mucinous components in prostate needle core biopsies or transurethral resection of the prostate specimens are also referred to as 'prostatic adenocarcinoma with mucinous features.' Mucinous adenocarcinoma of the prostatic urethra (mucin-producing urothelial-type adenocarcinoma of the prostate) as the name implies, does not arise from prostatic acini or ducts, and is a distinct entity that arises from the prostatic urethra usually from urethritis glandularis or glandular metaplasia with malignant transformation, and is analogous to adenocarcinoma with mucinous differentiation arising from the urinary bladder. This tumor is aggressive and has a relatively poor prognosis. The most common secondary tumors that arise from adjacent organs and spread (direct extension or metastasis) to the prostate gland, include urothelial carcinoma of the bladder and colorectal adenocarcinoma. Other secondary tumors that may involve the prostate include metastatic epithelial tumors from several other sites, malignant melanoma and soft tissue tumors.

Prostate cancer grading: a decade after the 2005 modified system

This review article will cover the evolution of grading of prostate cancer from the original Gleason system in the 1960-1970s to a more patient-centric grading system proposed in 2013 from a group at Johns Hopkins Hospital, validated in 2014 by a large multi-institutional study, and subsequently accepted by the World Health Organization (WHO), College of American Pathology (CAP), and the AJCC TNM system. Covered topics include: (1) historical background; (2) 2005 and 2014 International Society of Urological Pathology Grading Conferences; (3) Description of Gleason patterns; (4) new approaches to display Gleason grades; (5) grading variants and variations of acinar adenocarcinoma; (6) reporting rules for Gleason grading reporting secondary patterns of higher grade when present to a limited extent; (7) reporting secondary patterns of lower grade when present to a limited extent; (8) reporting percentage pattern 4; (9) general applications of the Gleason grading system; (10) needle biopsy with different cores showing different grades; (11) radical prostatectomy specimens with separate tumor nodules; and (12) a new grading system for prostate cancer.

Histopathology of Prostate Cancer

This review focuses on histopathological aspects of carcinoma of the prostate. A tissue diagnosis of adenocarcinoma is often essential for establishing a diagnosis of prostate cancer, and the foundation for a tissue diagnosis is currently light microscopic examination of hematoxylin and eosin (H&E)-stained tissue sections. Markers detected by immunohistochemistry on tissue sections can support a diagnosis of adenocarcinoma that is primary in the prostate gland or metastatic. Histological variants of carcinoma of the prostate are important for diagnostic recognition of cancer or as clinicopathologic entities that have prognostic and/or therapeutic significance. Histological grading of adenocarcinoma of the prostate, including use of the 2014 International Society of Urological Pathology (ISUP) modified Gleason grades and the new grade groups, is one of the most powerful prognostic indicators for clinically localized prostate cancer, and is one of the most critical factors in determination of management of these patients.

[The 2014 consensus conference of the ISUP on Gleason grading of prostatic carcinoma]

In 2005 the International Society of Urological Pathology (ISUP) held a concensus conference on Gleason grading in order to bring this grading system up to the current state of contemporary practice; however, it became clear that further modifications on the grading of prostatic carcinoma were necessary. The International Society of Urological Pathology therefore held a further consensus conference in 2014 to clarify these points. This article presents the essential results of the Chicago grading meeting.

Validation of International Society of Urological Pathology (ISUP) grading for prostatic adenocarcinoma in thin core biopsies using TROG 03.04 'RADAR' trial clinical data

In 2014 a consensus conference convened by the International Society of Urological Pathology (ISUP) adopted amendments to the criteria for Gleason grading and scoring (GS) for prostatic adenocarcinoma. The meeting defined a modified grading system based on 5 grading categories (grade 1, GS 3+3; grade 2, GS 3+4; grade 3, GS 4+3; grade 4, GS 8; grade 5, GS 9-10). In this study we have evaluated the prognostic significance of ISUP grading in 496 patients enrolled in the TROG 03.04 RADAR Trial. There were 19 grade 1, 118 grade 2, 193 grade 3, 88 grade 4 and 79 grade 5 tumours in the series, with follow-up for a minimum of 6.5 years. On follow-up 76 patients experienced distant progression of disease, 171 prostate specific antigen (PSA) progression and 39 prostate cancer deaths. In contrast to the 2005 modified Gleason system (MGS), the hazards of the distant and PSA progression endpoints, relative to grade 2, were significantly greater for grades 3, 4 and 5 of the 2014 ISUP grading scheme. Comparison of predictive ability utilising Harrell's concordance index, showed 2014 ISUP grading to significantly out-perform 2005 MGS grading for each of the three clinical endpoints.

Changes in prostate cancer grading: Including a new patient-centric grading system

The first structured approach to grade prostate cancer based on the underlying histological architecture was developed by Donald Gleason who in 1966 proposed a morphologic classification of prostate cancer and in 1974 demonstrated its clinical significance based on prostate cancer-specific death. Contemporarily referred to as the Gleason grading system, it has gained worldwide recognition allowing a more individualized approach to patients with prostate cancer. In 2005, the International Society of Urologic Pathology (ISUP) made the first revisions to the grading system. Subsequently, based on the new discoveries in pathologic and clinical aspects of prostate cancer, as well as the changing nature of the prostate cancer in part due to a robust screening, there was a need for experts to re-visit the approach to grade prostate cancer. In November 2014, the ISUP experts and clinical leaders in prostate cancer from 17 countries conducted a consensus conference in Chicago, IL, USA. The consensus conference defined various grade patterns and proposed the adoption of a new grading system of prostate cancer. Herein, we describe the background and rationale for the changes and provide guidelines to their clinical implementation.

Grading of prostatic adenocarcinoma: current state and prognostic implications

Background

Despite significant changes in the clinical and histologic diagnosis of prostate cancer, the Gleason grading system remains one of the most powerful prognostic predictors in prostate cancer. The correct diagnosis and grading of prostate cancer is crucial for a patient’s prognosis and therapeutic options. However, this system has undergone significant revisions and continues to have deficiencies that can potentially impact patient care.

Main Body

We describe the current state of grading prostate cancer, focusing on the current guidelines for the Gleason grading system and recent changes from the 2014 International Society of Urological Pathology Consensus Conference on Gleason Grading of Prostatic Carcinoma. We also explore the limitations of the current Gleason grading system and present a validated alternative to the Gleason score. The new grading system initially described in 2013 in a study from Johns Hopkins Hospital and then validated in a multi-institutional study, includes five distinct Grade Groups based on the modified Gleason score groups. Grade Group 1 = Gleason score ≤6, Grade Group 2 = Gleason score 3 + 4 = 7, Grade Group 3 = Gleason score 4 + 3 = 7, Grade Group 4 = Gleason score 8, Grade Group 5 = Gleason scores 9 and 10.

Conclusion

As this new grading system is simpler and more accurately reflects prostate cancer biology, it is recommended by the World Health Organization (WHO) to be used in conjunction with Gleason grading.

Prostate Cancer Grading: A Decade After the 2005 Modified Gleason Grading System

Since 1966, when Donald Gleason, MD, first proposed grading prostate cancer based on its histologic architecture, there have been numerous changes in clinical and pathologic practices relating to prostate cancer. Patterns 1 and 2, comprising more than 30% of cases in the original publications by Gleason, are no longer reported on biopsy and are rarely diagnosed on radical prostatectomy. Many of these cases may even have been mimickers of prostate cancer that were described later with the use of contemporary immunohistochemistry. The original Gleason system predated many newly described variants of prostate cancer and our current concept of intraductal carcinoma. Gleason also did not describe how to report prostate cancer on biopsy with multiple cores of cancer or on radical prostatectomy with separate tumor nodules. To address these issues, the International Society of Urological Pathology first made revisions to the grading system in 2005, and subsequently in 2014. Additionally, a new grading system composed of Grade Groups 1 to 5 that was first developed in 2013 at the Johns Hopkins Hospital and subsequently validated in a large multi-institutional and multimodal study was presented at the 2014 International Society of Urological Pathology meeting and accepted both by participating pathologists as well as urologists, oncologists, and radiation therapists. In the present study, we describe updates to the grading of prostate cancer along with the new grading system.

Metastatic Mucinous Adenocarcinoma of the Prostate with PSA Value of 8.6 ng/mL at 5-Year-Followup after Prostatectomy, Radiotherapy, and Androgen Deprivation

Introduction. Mucinous adenocarcinoma of the prostate is a rare variant of prostate cancer. Its malignant potential and the clinical course of the affected patients remain, by and large, controversial. No data exist about the course of metastatic mucinous adenocarcinoma of the prostate. Case Presentation. This case report describes the excellent clinical course of a 68-year-old patient with metastatic mucinous adenocarcinoma of the prostate, treated by radical prostatectomy, irradiation, and androgen deprivation. Conclusion. In our case, mucinous adenocarcinoma of the prostate does not appear to behave differently than acinar prostate cancer. Its malignant potential is dependent on its Gleason score.

ERG expression in mucinous prostatic adenocarcinoma and prostatic adenocarcinoma with mucinous features: comparison with conventional prostatic adenocarcinoma

TMPRSS2-ERG is the most common gene fusion in conventional prostatic adenocarcinoma (PCa), identified in about 40% to 70% of cases. Mucinous PCa and PCa with mucinous features are rare subtypes of prostate cancer, and ERG expression in these subtypes has not been well characterized in a large series. A search was made through the surgical pathology and expert consultation files of 2 major academic institutions for cases of mucinous PCa and PCa with mucinous features. The former were obtained from radical prostatectomy cases and the latter from radical prostatectomy cases, transurethral resection of the prostate, and prostate needle core biopsies. A tissue microarray composed of additional cases of mucinous PCa was also included in the study. Immunohistochemical stains for ERG were performed on all the cases. A total of 51 cases of mucinous PCa and PCa with mucinous features were identified. Twenty-five of 51 (47%) cases were positive for ERG expression, including 10/24 (42%) radical prostatectomy specimens, 7/14 (50%) biopsies, 2/4 (50%) transurethral resection of the prostate specimens, 6/9 (67%) from a tissue microarray. This is the largest study to date specifically characterizing ERG expression in mucinous PCa and PCa with mucinous features, with emphasis on comparison with adjacent conventional PCa. ERG is expressed in almost 50% of cases of mucinous PCa and PCa with mucinous features, similar to rates of expression in conventional PCa. This study strongly suggests that these rare subtypes of PCa are clonally related to conventional PCa.

Gleason score 7 adenocarcinoma of the prostate with lymph node metastases: analysis of 184 radical prostatectomy specimens

CONTEXT

Prostate cancer (PC) with lymph node metastases (LN(+)) is relatively rare, whereas it is relatively common in disease with a Gleason score (GS) 8 to 10 and virtually never seen in PC with GS 6 or less. It is most variable in GS 7 PC.

OBJECTIVE

To determine clinicopathologic features associated with GS 7 PC with LN(+) compared with a control group without lymph node metastases (LN(-)).

DESIGN

We analyzed 184 GS 7 radical prostatectomies with LN(+) and the same number of LN(-) Gleason-matched controls. The LN(+) cases were GS 3 + 4 = 7 (n = 64; 34.8%), GS 4 + 3 = 7 (n = 66; 35.9%), GS 3 + 4 = 7 with tertiary 5 (n = 10; 5.4%), and GS 4 + 3 = 7 with tertiary 5 (n = 44; 23.9%).

RESULTS

The LN(+) cases demonstrated higher average values in preoperative prostate-specific antigen (12.2 versus 8.1 ng/mL), percentage of positive biopsy cores (59.1% versus 42.9%), prostate weight (54.4 versus 49.4 g), number of LNs submitted (12.7 versus 9.4), incidence of nonfocal extraprostatic extension (82.6% versus 63.6%), tumor volume (28.9% versus 14.8%), frequency of lymphovascular invasion (78.3% versus 38.6%), intraductal spread of carcinoma (42.4% versus 20.7%), incidence of satellite tumor foci (16.4% versus 4.3%), incidence of pT3b disease (49.5% versus 14.7%), and lymphovascular invasion in the seminal vesicles (52% versus 30%). There were differences in GS 4 patterns and cytology between LN(+) and LN(-) cases, with the former having higher volumes of cribriform and poorly formed patterns, larger nuclei and nucleoli, and more-frequent macronucleoli. All P ≤ .05.

CONCLUSION

Gleason score 7 PC with LN(+) has features highlighting a more-aggressive phenotype. These features can be assessed as prognostic markers in GS 7 disease on biopsy (eg, GS 4 pattern, intraductal spread, cytology) or at radical prostatectomies (all variables), even in men without LN dissection or LN(-) disease.

Mucin-producing tumors and tumor-like lesions involving the prostate: a comprehensive review

Mucin-producing tumors of the prostate include both primary and secondary tumors with mucinous differentiation or features involving the prostate gland. These tumors are relatively rare and have variable prognostic and therapeutic implications. Primary mucinous (colloid) adenocarcinoma of the prostate is defined as prostatic adenocarcinoma with mucinous differentiation involving 25% or more of the entire tumor. Another primary tumor of the prostate that may have mucinous features is primary mucin-producing urothelial-type adenocarcinoma of the prostate (mucinous prostatic urethral adenocarcinoma). Primary mucin-producing urothelial-type adenocarcinoma of the prostate is a distinct entity that typically arises from the prostatic urethra possibly from urethritis glandularis or glandular metaplasia with malignant transformation, and it is analogous to adenocarcinoma with mucinous differentiation arising from the urinary bladder. Signet ring cell tumors of the prostate, though rare, may also have mucinous features. Secondary tumors with mucinous differentiation that may involve the prostate include adenocarcinomas of the urinary bladder and colorectum. Pathologists should also be aware of mucin-producing tumor-like lesions involving the prostate, including mucinous metaplasia, and benign Cowper glands that may mimic malignancy. Herein we present an updated and comprehensive review of the clinicopathologic, immunohistochemical, molecular, and prognostic features of mucinous tumors and tumor-like lesions involving the prostate gland, with emphasis on mucinous prostatic adenocarcinoma and its mimickers, including potential diagnostic pitfalls.

Variants and unusual patterns of prostate cancer: clinicopathologic and differential diagnostic considerations

Beyond the typical acinar morphology observed in the majority of prostatic adenocarcinomas, a spectrum of morphologic variants and prostate cancer subtypes exists. These unusual entities may be classified as: (1) cancer morphologies arising by divergent differentiation of prostatic ductal, acinar, or basal cells and associated with unique clinical features and/or therapeutic approaches, and (2) histologies occurring in the context of usual prostatic adenocarcinoma that may result in diagnostic misinterpretation or difficulties in Gleason grade assignment, especially in limited samples. This article details a number of variants, with emphasis on diagnostic criteria, differential diagnoses, and clinical significance.

A comprehensive review of incidence and survival in patients with rare histological variants of prostate cancer in the United States from 1973 to 2008

BACKGROUND

The American Joint Commission on Cancer (AJCC) identifies five rare variants of prostate adenocarcinoma: mucinous, ductal, signet ring cell, adenosquamous and neuroendocrine including small cell. No prior study has comprehensively detailed incidence and outcomes for all AJCC variants of prostate cancer.

METHODS

We used the Surveillance, Epidemiology and End Results (SEER) program to analyze prostate cancers diagnosed from 1973 to 2008. Cases of mucinous, ductal, signet ring cell, adenosquamous and neuroendocrine carcinoma were identified, along with cases of non-variant adenocarcinoma for comparison. Age-adjusted incidence rates (IRs) and overall survival (OS) were evaluated and stratified by race, age, stage and PSA. All IRs represent the number of cases per million people per year.

RESULTS

Each variant is rare, with IRs between 0.03 (adenosquamous) and 0.61 (mucinous). There was a significant difference in incidence between Caucasian and African American patients with mucinous adenocarcinoma. Median OS varied ranged from 10.0 months in neuroendocrine carcinoma to 125.0 months in mucinous adenocarcinoma. In all, 5-year OS ranged from 12.6% in neuroendocrine carcinoma to 75.1% in mucinous adenocarcinoma. There was a significant difference in survival between Caucasian and African American patients for mucinous adenocarcinoma (median survival 144.0 vs 99.0 months, P<0.01). African American patients with mucinous adenocarcinoma also presented with more advanced stage disease compared with Caucasian patients. Multivariate analysis demonstrated that African American race was not associated with worse survival when corrected for stage.

CONCLUSIONS

There are differences in IRs and OS among rare variants of prostate cancer. For mucinous adenocarcinoma, there are significant differences in incidence and survival between Caucasian and African American patients. These differences should be considered in clinical decision making for patients with these malignancies.

Digital quantification of five high-grade prostate cancer patterns, including the cribriform pattern, and their association with adverse outcome

Proper grading of the cribriform prostate cancer pattern has not previously been supported by outcome-based evidence. Among 153 men who underwent radical prostatectomy, 76 with prostate-specific antigen (PSA) failure (≥0.2 ng/mL [0.2 μg/L]) were matched to 77 without failure. Frequencies of high-grade patterns included fused small acini, 83.7%; papillary, 52.3%; large cribriform, 37.9%; small (≤12 lumens) cribriform, 17.0%; and individual cells, 22.9%. A cribriform pattern was present in 61% (46/76) of failures but 16% (12/77) of nonfailures (P < .0001). Multivariate analysis showed the cribriform pattern had the highest odds ratio for PSA failure, 5.89 (95% confidence interval, 2.53-13.70; P < .0001). The presence of both large and small cribriform patterns was significantly linked to failure. The cumulative odds ratio of failure per added square millimeter of cribriform pattern was 1.173 (P = .008), higher than for any other pattern. All 8 men with a cribriform area sum of 25 mm(2) or more had failure (range, 33-930). Regrading cribriform cancer as Gleason 5 improved the grade association with failure, although half of all cases with individual cells also had a cribriform pattern, precluding a precise determination of the independent importance of the latter. The cribriform pattern has particularly adverse implications for outcome.

TMPRSS2-ERG gene fusion is associated with low Gleason scores and not with high-grade morphological features

TMPRSS2-ERG gene rearrangement is seen in about half of clinically localized prostate cancers, yet controversy exists with regard to its prognostic implications. Similarly, the relationship of TMPRSS2-ERG fusion to Gleason score and morphology remains uncertain. We assigned Gleason scores and recorded morphological features for 521 clinically localized prostate cancers sampled in triplicate and arrayed in eight tissue microarray blocks. Fluorescence in situ hybridization was performed to delineate TMPRSS2-ERG aberrations. Using maximum Gleason score, based on three core evaluation, and overall Gleason score, based on prostatectomy sections, Fisher's exact test was performed for tumors with TMPRSS2-ERG translocation/deletion, copy number increase (≥ 3) of the TMPRSS2-ERG region without translocation/deletion, and copy number increase and concomitant translocation/deletion. In all, 217 (42%) translocation/deletion and 30 (5.9%) copy number increase-alone cases were detected. Among 217 translocation/deletion cases, 32 had translocation/deletion with copy number increase. In all, 237, 200, and 75 cancers had maximum core-specific Gleason score of 6, 7, and 8-10, respectively. Tumors with translocation/deletion tended toward lower Gleason scores than those without (P=0.002) with similar results for overall Gleason score (P=0.02); copy number increase cases tended toward higher Gleason scores than those without (P<0.001). Gleason score of 8-10 tumors demonstrated lower odds of translocation/deletion (odds ratio (OR) 0.38; 95% CI 0.21-0.68) and higher odds of copy number increase alone (OR 7.33; 95% CI 2.65-20.31) or copy number increase+translocation/deletion (OR 3.03; 95% CI 1.12-8.15) relative to Gleason score of <7 tumors. No significant difference in TMPRSS2-ERG incidence was observed between patients with and without cribriform glands, glomerulations, signet-ring cells, or intraductal cancer (P=0.821, 0.095, 0.132, 0.375). TMPRSS2-ERG gene fusion is associated with lower core-specific and overall Gleason scores and not with high-grade morphologies. Conversely, TMPRSS2-ERG copy number increase, with or without rearrangement, is associated with higher Gleason score. These findings indicate that translocation/deletion of TMPRSS2-ERG is not associated with histological features of aggressive prostate cancer.

Radical exenteration surgery is curative in locally advance mucinous prostatic adenocarcinoma involving bladder and rectum

The management of mucinous prostatic adenocarcinoma include hormonal treatment, radiotherapy and radical prostatectomy with variable long-term outcome. We report a 59 year old man with advanced mucinous prostatic adenocarcinoma involving almost the entire bladder and had failed treatment with hormonal and radiotherapy, but subsequently underwent radical pelvic exenteration surgery that resulted in long-term cure. He remains alive, his PSA remains undetectable and his surveillance CT scans did not show any evidence of recurrence after 11 years post-surgery. The favourable outcome of radical surgery suggests that radical surgery should be considered, especially in cases with failed initial treatments.

Variants and Unusual Patterns of Prostate Cancer

Beyond the typical acinar morphology observed in most prostatic adenocarcinoma, a spectrum of morphologic variants and prostate cancer subtypes exists. These unusual entities may be further classified into (1) cancer morphologies arising by divergent differentiation of prostatic ductal, acinar, or basal cells and associated with unique clinical features or therapeutic approaches, and (2) histologies occurring in the context of usual prostatic adenocarcinoma that may result in diagnostic misinterpretation or difficulties in Gleason grade assignment, especially in limited samples. This article details several variants, with emphasis on diagnostic criteria, differential diagnoses, and clinical significance.