Morphological changes induced by androgen blockade in normal prostate and prostatic carcinoma

Reprint of: morphologic spectrum of treatment-related changes in prostate tissue and prostate cancer: an updated review

A wide range of treatment options are available to patients with prostate cancer. Some treatments are standard (currently used) while some are emerging therapies. Androgen deprivation therapy is typically reserved for localized or metastatic prostate cancer not amenable to surgery. Radiation therapy may be offered to individuals for local therapy with curative intent in low- or intermediate-risk disease that may have a high probability of progression on active surveillance or where surgery is not suitable. Focal therapy/ablation treatment is an alternative approach for those who prefer to avoid radical prostatectomy for localized disease of low- or intermediate-risk or as salvage therapy after failed radiation therapy. Chemotherapy and immunotherapy remain under investigation and are currently used for androgen-independent disease or hormone-refractory prostate cancer; however, a better understanding of therapeutic efficacy is needed. Histopathologic changes observed in benign and malignant prostate tissue induced by hormonal therapies and radiation therapy are well described, whereas treatment-related effects secondary to novel therapies continue to be documented although their clinical significance is not absolutely clear. An informed and accurate evaluation of post-treatment prostate specimens requires pathologists with diagnostic acumen and knowledge relating to the histopathologic spectrum associated with each treatment option. In situations when clinical history is lacking, but morphologic features are suggestive of prior treatment, pathologists are encouraged to consult clinical colleagues regarding prior treatment history including details of when treatment was initiated and duration of therapy. This review aims to provide a concise update of current and emerging therapies for prostate cancer, histologic alterations and recommendations on Gleason grading.

Morphologic spectrum of treatment-related changes in prostate tissue and prostate cancer: An Updated Review

A wide range of treatment options is available to patients with prostate cancer. Some treatments are standard (currently used) while some are emerging therapies. Androgen deprivation therapy is typically reserved for localized or metastatic prostate cancer not amenable to surgery. Radiation therapy may be offered to individuals for local therapy with curative intent in low- or intermediate-risk disease that may have a high probability of progression on active surveillance or where surgery is not suitable. Focal therapy/ablation treatment is an alternative approach for those who prefer to avoid radical prostatectomy for localized disease of low- or intermediate-risk or as salvage therapy following failed radiation therapy. Chemotherapy and immunotherapy remain under investigation and are currently used for androgen-independent disease or hormone-refractory prostate cancer; however a better understand therapeutic efficacy is needed. Histopathologic changes observed in benign and malignant prostate tissue induced by hormonal therapies and radiation therapy is well described, while treatment-related effects secondary to novel therapies continue to be documented although their clinical significance is not absolutely clear. An informed and accurate evaluation of post-treatment prostate specimens requires pathologists with diagnostic acumen and knowledge relating to the histopathologic spectrum associated with each treatment option. In situations when clinical history is lacking, but morphologic features are suggestive of prior treatment, pathologists are encouraged to consult clinical colleagues regarding prior treatment history including details of when treatment was initiated and duration of therapy. This review aims to provide a concise update of current and emerging therapies for prostate cancer, histologic alterations and recommendations on Gleason grading.

Modeling Androgen Deprivation Therapy-Induced Prostate Cancer Dormancy and Its Clinical Implications

Treatment-induced tumor dormancy is a state in cancer progression where residual disease is present but remains asymptomatic. Dormant cancer cells are treatment-resistant and responsible for cancer recurrence and metastasis. Prostate cancer treated with androgen-deprivation therapy (ADT) often enters a dormant state. ADT-induced prostate cancer dormancy remains poorly understood due to the challenge in acquiring clinical dormant prostate cancer cells and the lack of representative models. In this study, we aimed to develop clinically relevant models for studying ADT-induced prostate cancer dormancy. Dormant prostate cancer models were established by castrating mice bearing patient-derived xenografts (PDX) of hormonal naïve or sensitive prostate cancer. Dormancy status and tumor relapse were monitored and evaluated. Paired pre- and postcastration (dormant) PDX tissues were subjected to morphologic and transcriptome profiling analyses. As a result, we established eleven ADT-induced dormant prostate cancer models that closely mimicked the clinical courses of ADT-treated prostate cancer. We identified two ADT-induced dormancy subtypes that differed in morphology, gene expression, and relapse rates. We discovered transcriptomic differences in precastration PDXs that predisposed the dormancy response to ADT. We further developed a dormancy subtype-based, predisposed gene signature that was significantly associated with ADT response in hormonal naïve prostate cancer and clinical outcome in castration-resistant prostate cancer treated with ADT or androgen-receptor pathway inhibitors.

IMPLICATIONS

We have established highly clinically relevant PDXs of ADT-induced dormant prostate cancer and identified two dormancy subtypes, leading to the development of a novel predicative gene signature that allows robust risk stratification of patients with prostate cancer to ADT or androgen-receptor pathway inhibitors.

Neoadjuvant hormonal therapy before radical prostatectomy in high-risk prostate cancer

Patients with high-risk prostate cancer treated with curative intent are at an increased risk of biochemical recurrence, metastatic progression and cancer-related death compared with patients treated for low-risk or intermediate-risk disease. Thus, these patients often need multimodal therapy to achieve complete disease control. Over the past two decades, multiple studies on the use of neoadjuvant treatment have been performed using conventional androgen deprivation therapy, which comprises luteinizing hormone-releasing hormone agonists or antagonists and/or first-line anti-androgens. However, despite results from these studies demonstrating a reduction in positive surgical margins and tumour volume, no benefit has been observed in hard oncological end points, such as cancer-related death. The introduction of potent androgen receptor signalling inhibitors (ARSIs), such as abiraterone, apalutamide, enzalutamide and darolutamide, has led to a renewed interest in using neoadjuvant hormonal treatment in high-risk prostate cancer. The addition of ARSIs to androgen deprivation therapy has demonstrated substantial survival benefits in the metastatic castration-resistant, non-metastatic castration-resistant and metastatic hormone-sensitive settings. Intuitively, a similar survival effect can be expected when applying ARSIs as a neoadjuvant strategy in high-risk prostate cancer. Most studies on neoadjuvant ARSIs use a pathological end point as a surrogate for long-term oncological outcome. However, no consensus yet exists regarding the ideal definition of pathological response following neoadjuvant hormonal therapy and pathologists might encounter difficulties in determining pathological response in hormonally treated prostate specimens. The neoadjuvant setting also provides opportunities to gain insight into resistance mechanisms against neoadjuvant hormonal therapy and, consequently, to guide personalized therapy.

Morphological and functional alterations of the prostate tissue during clinical progression in hormonally-naïve, hormonally-treated and castration-resistant patients with metastatic prostate cancer

Since commony used tools in oncological practice for the diagnosis of castration-resistent prostatic acinar adenocarcinoma are based on clinical criteria, such as castrate testosterone level, continuous rise in serum prostate-specific antigen, progression of preexisting disease or appearance of new metastases, it is important to identify reliable histopathological markers for the identification of this disease. Therefore, the aim of the present study was to determine the association between results from histological analysis, ultrastructural analysis and apoptosis in the prostate of patients with metastatic acinar prostatic adenocarcinoma (mPC). Patients were treated with androgen deprivation therapy (ADT), abiraterone acetate (Abi) therapy or received no treatment. Prostate tissue samples were divided into four groups as follows: i) Group 1, tissues from patients with benign prostatic hyperplasia (adenocarcinoma negative); ii) group 2, tissues from patients with metastatic hormone naïve prostate cancer; iii) group 3, tissues from patients with mPC treated with ADT; and iv) group 4, tissues from patients with metastatic castration-resistant prostate cancer treated with ADT and Abi. Immunohistochemical, terminal deoxynucleotidyl-transferase-mediated dUTP nick end labelling (TUNEL) and ultrastructural assays using light, fluorescence and transmission electron microscopy, respectively, were used to analyze prostate tissue samples. The results demonstrated that ADT and Abi therapy caused histological and ultrastructural changes in prostate tissues. In groups 3 and 4, benign and malignant tissues were affected by the hormonal therapy. Histologically, the malignant epithelium after ADT therapy in groups 3 and 4 presented with a loss of glandular architecture, nuclear and nucleolar shrinkage, chromatin condensation and cytoplasmic clearing. At the ultrastructural level, compact hypertrophic and hyperchromatic nuclei with numerous invaginations were observed in groups 2, 3 and 4. In addition, the incidence of abnormal mitochondria in malignant cells of these groups was high. Group 4 was characterized by the presence of malignant mesenchyme-like cells in the prostatic stroma, arranged in small groups surrounded by collagen fibrils. Furthermore, the cytoplasm of these cells contained filaments. A decrease in the number of apoptotic cells using TUNEL assays in the examined samples was observed with increasing disease progression. The findings from the present study suggest that the duration of treatment with ADT and progression of the disease were associated with apoptosis dysregulation.

Treatment effects in prostate cancer

Nonsurgical treatments for prostate cancer include androgen-deprivation therapy (ADT), radiation therapy (RT), ablative therapies, chemotherapy, and newly emerging immunotherapies. These approaches can be used alone or in combination depending on the clinical scenario. ADT is typically reserved for high-risk locally or systemically advanced disease that is not amenable to curative surgery. Radiation therapy can be used instead of surgery as primary therapy with curative intent for low-intermediate-risk disease as well as for control of locally advanced disease not suitable for surgery. Ablative therapies can be used as primary therapy for low-intermediate-risk disease or as salvage therapy for clinically localized disease where RT has failed. Chemotherapy and immune-based therapies are currently used for androgen-independent disease, although the indications for these approaches may well change as new data from clinical trials accrue. Pathologists should be able to recognize tissue changes associated with these treatments to provide information that will optimize patient management. This is particularly true in situations where clinical history of recent or remote nonsurgical treatment is not provided with the specimen. In the absence of this information, pathologists encountering the features described herein are encouraged to review patient records or communicate directly with clinical colleagues to determine how a given patient was treated and when.

A Novel System for Estimating Residual Disease and Pathologic Response to Neoadjuvant Treatment of Prostate Cancer

BACKGROUND

Pathologic variables that characterize response of prostate carcinoma to current neoadjuvant therapy have not been characterized in detail. This study reports (i) the histological features of prostate cancer treated with abiraterone and enzalutamide and inter-pathologist variance in identifying these features, and (ii) the effect of the novel androgen deprivation agents on residual cancer volume.

METHODS

We reviewed sections of prostatectomies from 37 patients treated with neoadjuvant agents and 22 untreated patients, tabulated the frequency of nine features of cancer (intact cancer glands, isolated cancer cells, poorly formed glands, cribriform architecture, clear spaces, intraductal carcinoma, solid sheets of cancer cells, prominent nucleoli, and previously described ABC grouping) and two features of benign glands (prominent basal cells and coalescent corpora amylacea). We used several methods, including a novel metric (visual grid system), to estimate residual tumor volume.

RESULTS

The most highly reproducible features were ABC grouping (κ = 0.56-0.7), presence of intraductal carcinoma (κ = 0.34-0.72), cribriform architecture (κ = 0.42-0.68), solid sheets of tumor cells (κ = 0.44-0.56), and coalescent corpora amylacea (κ = 0.4-0.54). Among poorly reproducible features were prominent nucleoli (κ = 0.03-0.11), clear spaces (κ = 0.05-0.07), and poorly formed cancer glands (κ = 0.02-0.1). Determination of tumor mass was excellent regardless of the method used-maximum tumor size (κ = 0.9-0.94), tumor area (κ = 0.94-0.96), and grid-based tumor cellularity (κ = 0.9).

CONCLUSIONS

We propose using a set of parameters including maximum tumor size, tumor area/volume, cellularity, volume, and ABC grouping for evaluating radical prostatectomies post-neoadjuvant therapy. Prostate 76:1285-1292, 2016. © 2016 Wiley Periodicals, Inc.

Undiagnosed prostatic malignancy at the time of radical cystoprostatectomy after prior prostatic radiation therapy

Purpose:

We determined the prevalence of prostatic malignancy in patients undergoing radical cystoprostatectomy (RC) for urothelial carcinoma (UC) with a history of radiation therapy (XRT) treatment for prostatic adenocarcinoma (PCa).

Materials and Methods:

Fifty-three men who underwent a RC for UC that were previously treated for PCa with XRT were retrospectively identified. Pathology reports were reviewed to assess for residual PCa or prostatic UC at the time of surgery.

Results:

Thirteen (25%) patients had residual PCa, 16 (30%) had prostatic UC, and 8 (15%) had both. Sixteen (30%) patients had no evidence of prostatic disease. Patients with PCa had median tumor volume of 2.2 cc (interquartile range: 1.2–2.5 cc) and one-third had high-risk features (Gleason score >8 or pT3-T4 disease). Sixteen of 24 patients (67%) with prostatic UC had a stromal invasion, 5 (21%) had a ductal invasion, and 3 (13%) had carcinoma in situ. Tumors at bladder neck or trigone during transurethral resection were predictive of prostatic UC (odds ratio: 4.32, 95% confidence interval: 1.2–15.5, P = 0.025).

Conclusions:

Despite prior XRT for PCa, less than one-third of patients had no prostatic disease at the time of RC. Routine prostatic sampling should be considered in these patients especially if considering the orthotopic diversion.

Prostate changes related to therapy: with special reference to hormone therapy

Hormone and radiation therapy have traditionally been used in prostate cancer (PCa). Morphological effects are often identified in needle biopsies and surgical specimens. A range of histological changes are seen in the non-neoplastic prostate and in the pre-neoplastic and neoplastic areas. Other ablative therapies, including cryotherapy, and emerging focal therapies, such as high-intensity focused ultrasound, photodynamic therapy and interstitial laser thermotherapy, may induce changes on the prostate. As new compounds are developed for prostate cancer treatment, it is important to document their effects on benign and neoplastic prostate tissue.

Analysis of prognostic factors in localized high-risk prostate cancer patients treated with HDR brachytherapy, hypofractionated 3D-CRT and neoadjuvant/adjuvant androgen deprivation therapy (trimodality therapy)

Trimodality therapy consisting of high dose rate (HDR) brachytherapy combined with external beam radiation therapy (EBRT), neoadjuvant hormonal therapy (NHT) and adjuvant hormonal therapy (AHT) has been used to treat localized high-risk prostate cancer. In this study, an analysis of patients receiving the trimodality therapy was performed to identify prognostic factors of biochemical relapse-free survival (bRFS). Between May 2005 and November 2008, 123 high-risk prostate cancer patients (D'Amico classification) were treated with NHT prior to HDR brachytherapy combined with hypofractionated EBRT. Among these patients, 121 had completed AHT. The patients were assigned by time to be treated with a low-dose or high-dose arm of HDR brachytherapy with subsequent hypofractionated 3D conformal radiation therapy (3D-CRT). Multivariate analysis was used to determine prognostic factors for bRFS. With a median follow-up of 60 months, the 5-year bRFS for all patients was 84.3% (high-dose arm, 92.9%; low-dose arm, 72.4%, P = 0.047). bRFS in the pre-HDR PSA ≤ 0.1 ng/ml subgroup was significantly improved compared with that in the pre-HDR PSA > 0.1 ng/ml subgroup (88.3% vs 68.2%, P = 0.034). On multivariate analysis, dose of HDR (P = 0.045, HR = 0.25, 95% CI = 0.038-0.97) and pre-HDR PSA level (P = 0.02 HR = 3.2, 95% CI = 1.18-10.16) were significant prognostic factors predicting bRFS. In high-risk prostate cancer patients treated with the trimodality therapy, the dose of HDR and pre-HDR PSA were significant prognostic factors. The pre-HDR PSA ≤ 0.1 subgroup had significantly improved bRFS. Further studies are needed to confirm the relevance of pre-HDR PSA in trimodality therapy.

Treatment effects in prostate cancer following traditional and emerging therapies

Treatment options for prostate cancer consist of radical prostatectomy, hormonal therapy and radiation therapy. Hormonal and radiation therapy have well-known, often profound, effects on the histological appearance of benign and malignant prostate tissue. Novel therapies including focal ablative treatments, chemotherapies and targeted molecular therapies are beginning to emerge and pathologists will play a central role in documenting the effects of these treatments at the tissue level. As such, knowledge of treatment-related changes and access to clinical information are essential to ensure accurate interpretation and reporting of post-treatment prostate specimens by pathologists.

The reasons behind variation in Gleason grading of prostatic biopsies: areas of agreement and misconception among 266 European pathologists

AIMS

The Gleason scoring system underwent revision at the International Society of Urological Pathology (ISUP) conference in 2005. It is not known how uropathologists have interpreted its recommendations.

METHOD AND RESULTS

A web-based survey to European Network of Uropathology members received replies from 266 pathologists in 22 countries. Eighty-nine per cent claimed to follow ISUP recommendations. Key areas of disagreement included the following. Smoothly rounded cribriform glands were assigned Gleason pattern (GP) 3 by 51% and GP 4 by 49%. Necrosis was diagnosed as GP 5 by 62%. Any amount of secondary pattern of higher grade in needle biopsies was included in the Gleason score by 58%. Tertiary GP of higher grade on needle biopsies was included in the Gleason score by only 58%. If biopsy cores were embedded separately, only 56% would give a Gleason score for each core/slide examined; 68% would give a concluding Gleason score and the most common method was a global Gleason score (77%). Among those who blocked multiple biopsy cores together, 46% would only give an overall Gleason score for the case.

CONCLUSION

Misinterpretation of ISUP 2005 is widespread, and may explain the variation in Gleason scoring seen. Clarity and uniformity in teaching ISUP 2005 recommendations is necessary.

Diagnostic utility of androgen receptor expression in discriminating poorly differentiated urothelial and prostate carcinoma

AIMS

Pathological separation of poorly differentiated urothelial and prostate carcinoma is difficult, but imperative because of the impact on patient management. Tumour morphology, in conjunction with a panel of immunohistochemistry (IHC), such as prostate-specific antigen (PSA), prostatic acid phosphatase (PSAP), CK7, CK20, p63 and high molecular weight keratins (HMWKs) are usually employed to resolve this issue. Androgen receptor (AR) expression is maintained in high-grade, undifferentiated prostate carcinoma, and thus, could be considered as a potentially useful adjunct to the conventional panel of markers.

METHODS

We performed an institutional review of all cases from 2006 to 2012 in which AR IHC had been performed to determine its diagnostic utility in discriminating between poorly differentiated urothelial and prostate carcinoma. Of the eligible cases (n=40), there were 9 high-grade urothelial carcinomas, 27 prostate carcinomas and 4 with both prostate and bladder tumours. All diagnoses were made by integrating the clinical, radiological, morphological and IHC results.

RESULTS

In all the prostate carcinomas, there was diffuse, intense nuclear staining for AR. The urothelial tumours were either negative, had cytoplasmic staining or showed occasionally weak nuclear staining. The difference was highly significant with p<0.0001 (Mann-Whitney U test).

CONCLUSIONS

We conclude that AR is an important marker as it is best able to distinguish between poorly differentiated urothelial and prostate carcinoma. AR appears superior to PSA and PSAP, which are not consistently expressed in high-grade prostate carcinoma. Also, high-grade urothelial carcinoma may be negative for CK20, p63/HMWK and occasionally CK7. We advocate the inclusion of AR in the panel of markers to differentiate these tumours.