Neuroanatomy of the normal prostate

Apparent differences in prostate zones: susceptibility to prostate cancer, benign prostatic hyperplasia and prostatitis

Men are inevitably plagued by prostate disease throughout their lives. However, the understanding of the pathogenesis of prostate diseases is still limited. In the 1960s, McNeal proposed the theory of prostate zones: the prostate was divided into three main zones: transition zone, central zone, and peripheral zone. Over the past 50 years, significant differences between different prostate zones have been gradually revealed. We summarized the most significant differences in different zones of the prostate. For the first time, we proposed the "apparent difference in prostate zones" concept. This new concept has been proposed to understand the different zones of the prostate better. It also provided new ideas for exploring the susceptibility of lesions in different prostate zones. Despite the reported differences between zones, the treatment of prostate-related diseases remains partition agnostic. Therefore, we also discussed the clinical significance of the "apparent difference in the prostate zone" and emphasized the necessity of prostate zones.

Target Volume Optimization for Localized Prostate Cancer

PURPOSE

To provide a comprehensive review of the means by which to optimize target volume definition for the purposes of treatment planning for patients with intact prostate cancer with a specific emphasis on focal boost volume definition.

METHODS

Here we conduct a narrative review of the available literature summarizing the current state of knowledge on optimizing target volume definition for the treatment of localized prostate cancer.

RESULTS

Historically, the treatment of prostate cancer included a uniform prescription dose administered to the entire prostate with or without coverage of all or part of the seminal vesicles. The development of prostate magnetic resonance imaging (MRI) and positron emission tomography (PET) using prostate-specific radiotracers has ushered in an era in which radiation oncologists are able to localize and focally dose-escalate high-risk volumes in the prostate gland. Recent phase 3 data has demonstrated that incorporating focal dose escalation to high-risk subvolumes of the prostate improves biochemical control without significantly increasing toxicity. Still, several fundamental questions remain regarding the optimal target volume definition and prescription strategy to implement this technique. Given the remaining uncertainty, a knowledge of the pathological correlates of radiographic findings and the anatomic patterns of tumor spread may help inform clinical judgement for the definition of clinical target volumes.

CONCLUSION

Advanced imaging has the ability to improve outcomes for patients with prostate cancer in multiple ways, including by enabling focal dose escalation to high-risk subvolumes. However, many questions remain regarding the optimal target volume definition and prescription strategy to implement this practice, and key knowledge gaps remain. A detailed understanding of the pathological correlates of radiographic findings and the patterns of local tumor spread may help inform clinical judgement for target volume definition given the current state of uncertainty.

Differences in the pathogenetic characteristics of prostate cancer in the transitional and peripheral zones and the possible molecular biological mechanisms

Since the theory of modern anatomical partitioning of the prostate was proposed, the differences in the incidence and pathological parameters of prostate cancer between the peripheral zone and transition zone have been gradually revealed. It suggests that there are differences in the pathogenic pathways and molecular biology of prostate cancer between different regions of origin. Over the past decade, advances in sequencing technologies have revealed more about molecules, genomes, and cell types specific to the peripheral and transitional zones. In recent years, the innovation of spatial imaging and multiple-parameter magnetic resonance imaging has provided new technical support for the zonal study of prostate cancer. In this work, we reviewed all the research results and the latest research progress in the study of prostate cancer in the past two decades. We summarized and proposed several vital issues and focused directions for understanding the differences between peripheral and transitional zones in prostate cancer.

Prostate zones and cancer: lost in transition?

Localized prostate cancer shows great clinical, genetic and environmental heterogeneity; however, prostate cancer treatment is currently guided solely by clinical staging, serum PSA levels and histology. Increasingly, the roles of differential genomics, multifocality and spatial distribution in tumorigenesis are being considered to further personalize treatment. The human prostate is divided into three zones based on its histological features: the peripheral zone (PZ), the transition zone (TZ) and the central zone (CZ). Each zone has variable prostate cancer incidence, prognosis and outcomes, with TZ prostate tumours having better clinical outcomes than PZ and CZ tumours. Molecular and cell biological studies can improve understanding of the unique molecular, genomic and zonal cell type features that underlie the differences in tumour progression and aggression between the zones. The unique biology of each zonal tumour type could help to guide individualized treatment and patient risk stratification.

The Etiology and Pathophysiology Genesis of Benign Prostatic Hyperplasia and Prostate Cancer: A New Perspective

Background: The etiology of benign prostatic hyperplasia and prostate cancer are unknown, with ageing being the greatness risk factor. Methods: This new perspective evaluates the available interdisciplinary evidence regarding prostate ageing in terms of the cell biology of regulation and homeostasis, which could explain the timeline of evolutionary cancer biology as degenerative, inflammatory and neoplasm progressions in these multifactorial and heterogeneous prostatic diseases. Results: This prostate ageing degeneration hypothesis encompasses the testosterone-vascular-inflamm-ageing triad, along with the cell biology regulation of amyloidosis and autophagy within an evolutionary tumorigenesis microenvironment. Conclusions: An understanding of these biological processes of prostate ageing can provide potential strategies for early prevention and could contribute to maintaining quality of life for the ageing individual along with substantial medical cost savings.

Complexity of Neural Component of Tumor Microenvironment in Prostate Cancer

The tumor microenvironment (TME) plays an essential role in the development and progression of neoplasms. TME consists of the extracellular matrix and numerous specialized cells interacting with cancer cells by paracrine and autocrine mechanisms. Tumor axonogenesis and neoneurogenesis constitute a developing area of investigation. Prostate cancer (PC) is one of the most common malignancies in men worldwide. During the past years, more and more studies have shown that mechanisms leading to the development of PC are not confined only to the epithelial cancer cell, but also involve the tumor stroma. Different nerve types and neurotransmitters present within the TME are thought to be important factors in PC biology. Moreover, perineural invasion, which is a common way of PC spreading, in parallel creates the neural niche for malignant cells. Cancer neurobiology seems to have become a new discipline to explore the contribution of neoplastic cell interactions with the nervous system and the neural TME component, also to search for potential therapeutic targets in malignant tumors such as PC.

Gene Editing of α6 Integrin Inhibits Muscle Invasive Networks and Increases Cell-Cell Biophysical Properties in Prostate Cancer

Human prostate cancer confined to the gland is indolent (low-risk), but tumors outside the capsule are aggressive (high-risk). Extracapsular extension requires invasion within and through a smooth muscle-structured environment. Because integrins respond to biomechanical cues, we used a gene editing approach to determine if a specific region of laminin-binding α6β1 integrin was required for smooth muscle invasion both in vitro and in vivo. Human tissue specimens showed prostate cancer invasion through smooth muscle and tumor coexpression of α6 integrin and E-cadherin in a cell-cell location and α6 integrin in a cell-extracellular matrix (ECM) distribution. Prostate cancer cells expressing α6 integrin (DU145 α6WT) produced a 3D invasive network on laminin-containing Matrigel and invaded into smooth muscle both in vitro and in vivo. In contrast, cells without α6 integrin (DU145 α6KO) and cells expressing an integrin mutant (DU145 α6AA) did not produce invasive networks, could not invade muscle both in vitro and in vivo, and surprisingly formed 3D cohesive clusters. Using electric cell-substrate impedance testing, cohesive clusters had up to a 30-fold increase in normalized resistance at 400 Hz (cell-cell impedance) as compared with the DU145 α6WT cells. In contrast, measurements at 40,000 Hz (cell-ECM coverage) showed that DU145 α6AA cells were two-fold decreased in normalized resistance and were defective in restoring resistance after a 1 μmol/L S1P challenge as compared with the DU145 α6WT cells. The results suggest that gene editing of a specific α6 integrin extracellular region, not required for normal tissue function, can generate a new biophysical cancer phenotype unable to invade the muscle, presenting a new therapeutic strategy for metastasis prevention in prostate cancer. SIGNIFICANCE: This study shows an innovative strategy to block prostate cancer metastasis and invasion in the muscle through gene editing of a specific α6 integrin extracellular region.

Vasa nervorum angiogenesis in prostate cancer with perineural invasion

BACKGROUND

Perineural invasion (PNI) is generally accepted as a major route of cancer dissemination in malignancies associated with highly enervated organs. However, the effect of cancer cells on vasa nervorum remains unknown. We studied this effect in locally advanced prostate cancer, a high-risk feature associated with approximately 20% of prostate cancer specific mortality.

METHODS

We used immunohistochemistry for CD34, fibroblast growth factor-2 (FGF-2), FSHR, podoplanin, vascular endothelial growth factor (VEGF), and VEGFR-2 as well as histochemical methods to examine the vasa nervorum of nerves invaded by cancer cells in tissue samples from 85 patients.

RESULTS

The percentage of the nerve area occupied by CD34-positive vasa nervorum endothelial cells in nerves with PNI was much higher than in nerves without PNI (7.3 ± 1.2 vs 1.9 ± 0.4; P < 0.001 and 5.8 ± 0.6 vs 1.23 ± 0.8; P < 0.001 in pT3a and pT3b prostate cancer specimens, respectively). In 19/85 of the patients the CD34-positive vasa nervorum microvessels have a thick basement membrane, similar to the vessels in diabetic microangiopathy. This subendothelial layer contains collagen fibers. Vasa nervorum endothelia and Schwann cells express FGF-2 (nuclear localization) and FSHR (plasma membrane and cytoplasmic staining). Prostate cancer cells invading nerves express VEGF, a critical cytokine in tumor angiogenesis. The vasa nervorum of prostatic nerves with PNI did not express detectable levels of VEGFR-2. No podoplanin-positive lymphatic vessels were seen in nerves.

CONCLUSION

In locally advanced prostate cancer, PNI of cancer cells is associated with formation of new endoneurial capillaries and changes of vasa nervorum morphology.

Generation and Regulation of Spontaneous Contractions in the Prostate

Spontaneous myogenic contractions have been shown to be significantly upregulated in prostate tissue collected from men with Benign Prostatic Hyperplasia (BPH), an extremely common disorder of the ageing male. Although originally thought likely to be involved in 'housekeeping' functions, mixing prostatic secretions to prevent stagnation, these spontaneous myogenic contractions provide a novel opportunity to understand and treat BPH. This treatment potential differs from previous models, which focused exclusively on attenuating nerve-mediated neurogenic contractions. Previous studies in the rodent prostate have provided an insight into the mechanisms underlying the regulation of myogenic contractions. 'Prostatic Interstitial Cells' (PICs) within the prostate appear to generate pacemaker potentials, which arise from the summation of number of spontaneous transient depolarisations triggered by the spontaneous release of Ca²⁺ from internal stores and the opening of Ca²⁺-activated Cl^- channels. Pacemaker potentials then conduct into neighbouring smooth muscle cells to generate spontaneous slow waves. These slow waves trigger the firing of 'spike-like' action potentials, Ca²⁺ entry and contraction, which are not attenuated by blockers of neurotransmission. However, these spontaneous prostatic contractions can be modulated by the autonomic nervous system. Here, we discuss the mechanisms underlying rodent and human prostate myogenic contractions and the actions of existing and novel pharmacotherapies for the treatment of BPH. Understanding the generation of human prostatic smooth muscle tone will confirm the mechanism of action of existing drugs, inform the identification and effectiveness of new pharmacotherapies, as well as predict patient outcomes.

Histological and quantitative analyzes of the stromal and acinar components of normal human prostate zones

BACKGROUND

McNeal divided the human prostate into three major anatomical areas: the peripheral zone (PZ), the central zone (CZ), and the transition zone (TZ). Each of these areas is biologically and histologically distinct. The PZ and TZ have clinical significance and are associated with prostate cancer (PC) and benign prostatic hyperplasia (BPH), respectively. Therefore, the objective of the present study was to quantitatively and qualitatively analyze the parenchymal and stromal components that constitute the different prostate zones.

METHODS

We assessed 19 samples from each prostate zone. The samples were obtained from necropsies of young people between 18 and 32 years of age with intact urogenital tracts. The samples were fixed in 4% buffered formalin and processed for paraffin embedding. Sections with a thickness of five micrometres were obtained from each sample. The sections were stained using histochemical and immunohistochemical techniques to identify the acinar and stromal components of each zone. Photomicrographs were obtained for morphometric analysis using an algorithm based on color segmentation. Data were analyzed using one-way analysis of variance (ANOVA) with the Bonferroni post-test. Differences with P < 0.05 were regarded as statistically significant.

RESULTS

Collagen fibres were more numerous in the TZ (+40.26%; P = 0.0230) than in the PZ. Muscle fibres were also more numerous in the TZ (+47.05%; P = 0.0120) than in the PZ. Elastic system fibres in the TZ significantly differed from those in the PZ (+84.61%; P = 0.0012) and the CZ (+61.66%; P = 0.0074). Similarly, nerves in the PZ (-42.86%; P = 0.0107) significantly differed from nerves in the CZ. Epithelial height was lower in the TZ than in the PZ (-30.17%; P = 0.0034) and the CZ (-25.01%; P = 0.0330).

CONCLUSION

Our objective, quantitative data regarding the various elements that constitute the normal prostate stroma allowed us to reveal differences among prostate zones. This study established patterns for normal parameters and may be used for posterior comparisons in histopathological analysis.

The Cohesive Metastasis Phenotype in Human Prostate Cancer

A critical barrier for the successful prevention and treatment of recurrent prostate cancer is detection and eradication of metastatic and therapy-resistant disease. Despite the fall in diagnoses and mortality, the reported incidence of metastatic disease has increased 72% since 2004. Prostate cancer arises in cohesive groups as intraepithelial neoplasia, migrates through muscle and leaves the gland via perineural invasion for hematogenous dissemination. Current technological advances have shown cohesive-clusters of tumor (also known as microemboli) within the circulation. Circulating tumor cell (CTC) profiles are indicative of disseminated prostate cancer, and disseminated tumor cells (DTC) are found in cohesive-clusters, a phenotypic characteristic of both radiation- and drug-resistant tumors. Recent reports in cell biology and informatics, coupled with mass spectrometry, indicate that the integrin adhesome network provides an explanation for the biophysical ability of cohesive-clusters of tumor cells to invade thorough muscle and nerve microenvironments while maintaining adhesion-dependent therapeutic resistance. Targeting cohesive-clusters takes advantage of the known ability of extracellular matrix (ECM) adhesion to promote tumor cell survival and represents an approach that has the potential to avoid the progression to drug- and radiotherapy-resistance. In the following review we will examine the evidence for development and dissemination of cohesive-clusters in metastatic prostate cancer.

Identification of beta-2 as a key cell adhesion molecule in PCa cell neurotropic behavior: a novel ex vivo and biophysical approach

Prostate cancer (PCa) is believed to metastasize through the blood/lymphatics systems; however, PCa may utilize the extensive innervation of the prostate for glandular egress. The interaction of PCa and its nerve fibers is observed in 80% of PCa and is termed perineural invasion (PNI). PCa cells have been observed traveling through the endoneurium of nerves, although the underlying mechanisms have not been elucidated. Voltage sensitive sodium channels (VSSC) are multimeric transmembrane protein complexes comprised of a pore-forming α subunit and one or two auxiliary beta (β) subunits with inherent cell adhesion molecule (CAM) functions. The beta-2 isoform (gene SCN2B) interacts with several neural CAMs, while interacting putatively with other prominent neural CAMs. Furthermore, beta-2 exhibits elevated mRNA and protein levels in highly metastatic and castrate-resistant PCa. When overexpressed in weakly aggressive LNCaP cells (2BECFP), beta-2 alters LNCaP cell morphology and enhances LNCaP cell metastasis associated behavior in vitro. We hypothesize that PCa cells use beta-2 as a CAM during PNI and subsequent PCa metastasis. The objective of this study was to determine the effect of beta-2 expression on PCa cell neurotropic metastasis associated behavior. We overexpressed beta-2 as a fusion protein with enhanced cyan fluorescence protein (ECFP) in weakly aggressive LNCaP cells and observed neurotropic effects utilizing our novel ex vivo organotypic spinal cord co-culture model, and performed functional assays with neural matrices and atomic force microscopy. With increased beta-2 expression, PCa cells display a trend of enhanced association with nerve axons. On laminin, a neural CAM, overexpression of beta-2 enhances PCa cell migration, invasion, and growth. 2BECFP cells exhibit marked binding affinity to laminin relative to LNECFP controls, and recombinant beta-2 ectodomain elicits more binding events to laminin than BSA control. Functional overexpression of VSSC beta subunits in PCa may mediate PCa metastatic behavior through association with neural matrices.

Biological correlates of prostate cancer perineural invasion diameter

Perineural invasion is a symbiotic relationship between cancer cells and nerves and is most frequently seen in "neurotropic" cancers such as prostate cancer. It results in increased perineural space cancer cell growth and decreased apoptosis and induces nerve growth. Tissue microarrays were constructed from 640 radical prostatectomy specimens with prostate cancer. The perineural diameter was measured as previously described. Multiple biomarkers have been previously performed on this tissue microarray cohort, and all data were kept in the same database. The biomarker results database was queried for correlations between perineural invasion diameter and tissue biomarkers. Increased perineural invasion diameter correlated with increased proliferation of prostate cancer cells and with apoptosis. It also correlated with proteins involved in survival pathways such as nuclear factor κB, c-Myc, phosphorylated AKT, and its downstream effector FHKR, but not with GSK. Unlike nerve density, it did not correlate with decreased PTEN expression. Increased perineural invasion diameter was associated with higher levels of hormonal receptors such as androgen receptor, but not estrogen receptor. Also associated with perineural invasion diameter were coregulators and corepressors including SRC1 and TIF2. Perineural invasion diameter had the strongest correlation with tumor volume (ρ = 0.579, P = .000), not identified with nerve density. These data demonstrate that perineural invasion has the same biologic correlations as neural density. However, we found a distinct and very strong correlation with increased tumor volume. These data confirm that perineural invasion is the ultimate and most successful interaction between cancer cells and nerve fibers, resulting in increased tumor growth.

TMPRSS2-ERG rearrangement in dominant anterior prostatic tumours: incidence and correlation with ERG immunohistochemistry

AIM

To study prostate cancer zonal differences in TMPRSS2-ERG gene rearrangement.

METHODS AND RESULTS

We examined 136 well-characterized dominant anterior prostatic tumours, including 61 transition zone (TZ) and 75 anterior peripheral zone (PZ) lesions, defined using strict anatomical considerations. TMPRSS2-ERG FISH and ERG protein immunohistochemistry were performed on tissue microarrays. FISH results, available for 56 TZ and 71 anterior PZ samples, were correlated with ERG staining and TZ-associated 'clear cell' histology. Fewer TZ cancers (four of 56; 7%) were rearranged than anterior PZ cancers (18 of 71; 25%) (P = 0.009); deletion was the sole mechanism of TZ cancer rearrangement. ERG protein overexpression was present in 4% (two of 56; both FISH+) and 30% (21 of 71; 17 FISH+) of TZ and anterior PZ tumours, respectively. 'Clear cell' histology was present in 21 of 56 (38%) TZ and eight of 71 (11%) anterior PZ tumours. Seven per cent of cancers with and 21% without this histology had rearrangement, regardless of zonal origin.

CONCLUSIONS

TMPRSS2-ERG rearrangement occurs in dominant TZ and anterior PZ prostate cancers, with all rearranged TZ cancers in this cohort showing deletion. ERG immunohistochemistry demonstrated excellent sensitivity (86%) and specificity (96%) for TMPRSS2-ERG rearrangement. TMPRSS2-ERG fusion is rare in TZ tumours and present at a low frequency in tumours displaying 'clear cell' histology.

Computerized quantification and planimetry of prostatic capsular nerves in relation to adjacent prostate cancer foci

BACKGROUND

Perineural invasion is discussed as a significant route of extraprostatic extension in prostate cancer (PCa). Recent in vitro studies suggested a complex mechanism of neuroepithelial interaction.

OBJECTIVE

The present study was intended to investigate whether the concept of neuroepithelial interaction can be supported by a quantitative analysis and planimetry of capsular nerves in relation to adjacent PCa foci.

DESIGN, SETTING, AND PARTICIPANTS

Whole-mount sections of the prostate were created from patients undergoing non-nerve-sparing laparoscopic radical prostatectomy. For each prostate, adjacent sections were created and stained both to identify capsular nerves (S100) and to localize cancer foci (hematoxylin and eosin).

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Computerized quantification and planimetry of capsular nerves (ImageJ software) were performed after applying a digital grid to define 12 capsular sectors. For statistical analyses, mixed linear models were calculated using the SAS 9.3 software package.

RESULTS AND LIMITATIONS

Specimens of 33 prostates were investigated. A total of 1957 capsular nerves and a total capsular nerve surface area of 26.44 mm(2) were measured. The major proportion was found in the dorsolateral (DL) region (p<0.001). Adjacent tumor was associated with a statistically significant higher capsular nerve count compared with the capsules of tumor-free sectors (p<0.005). Similar results were shown for capsular nerve surface area (p<0.006). Subsequent post hoc analyses at the sector level revealed that the effect of tumor on capsular nerve count or nerve surface area is most pronounced in the DL region.

CONCLUSIONS

The presence of PCa foci resulted in a significantly increased capsular nerve count and capsular nerve surface area compared with tumor-free sectors. The present study supports former in vitro findings suggesting that the presence of PCa lesions may lead to complex neuroepithelial interactions resulting in PCa-induced nerve growth.

Microvascularity in transition zone prostate tumors resembles normal prostatic tissue

BACKGROUND

The objective of this study was comparison of characteristics of the microvasculature in transition zone tumor (TZT) and benign nodular hyperplasia (BPH) with normal prostatic transition zone (NTZ), applying accurate and objective quantification based on digital image analysis. Results of this study may increase understanding of prostate dynamic contrast enhanced (DCE) MRI analysis.

METHODS

Radical prostatectomy specimens of 28 patients containing TZT ranging from pT2-pT4 were used. In 11 patients a concomitant peripheral zone tumor (PZT) was present. Microvessels were visualized by CD31 immunohistochemistry. Specimens were scanned using a computer-controlled microscope with automatic recognition of microvessels. Pseudocolor maps were produced displaying microvessel density, perimeter, and area of an entire prostate transection. Mean, 75th percentile (p75) and coefficient of variation (CV) were calculated automatically in manually indicated areas of the tumor and corresponding contralateral normal tissue, and BPH.

RESULTS

Large variability was seen in TZT microvascular parameters, indicating presence of patients having both hypo and hypervascularized tumors compared to NTZ. In contrast, areas of BPH showed a more consistent increase in vascular parameters, with decreased CV. Analysis of PZT confirmed results of our previous study, with mean and p75 of all vascular parameters being significantly increased and a decrease in CV. No correlation was found for clinicopathological parameters and microvascular parameters.

CONCLUSION

Microvasculature of transition zone tumor showed increased heterogeneity compared to BPH and peripheral zone tumors, possibly explaining the difficulty of TZT detection on DCE-MRI.

Perineural invasion as a predictor of extraprostatic extension of prostate cancer: a systematic review and meta-analysis

A systematic review of the literature was performed to assess the relationship between the presence of perineural invasion (PNI) at prostate biopsy and extraprostatic extension (EPE) of prostate cancer. In August 2012, Medline, Embase, Scopus and Web of Science databases were searched. A "free-text" protocol using the terms "perineural invasion prostate cancer" was applied. Studies published only as abstracts and reports from meetings were not included in this review. In total, 341 records were retrieved from Medline, 507 from Embase, 374 from Scopus and 65 from the Web of Science database. The records were reviewed to identify studies correlating the presence of PNI with that of EPE. A cumulative analysis was conducted using Review Manager software v. 5.1 (Cochrane Collaboration, Oxford, UK). In univariate analysis, PNI showed a statistically significant association with pT3 tumours (p < 0.00001), which could be observed for both pT3a (p < 0.0001) and pT3b (p < 0.0001). In conclusion, the cumulative analysis shows a statistically significant higher incidence of EPE in patients who had PNI at needle biopsy. The main limitation of the analysis was that it was not possible to perform a multivariate analysis. Further attempts to build a nomogram for the prediction of EPE could include the presence of PNI at needle biopsy.

Anatomy of the prostate revisited: implications for prostate biopsy and zonal origins of prostate cancer

Over the past 25 years, our understanding of prostatic disease has evolved secondary to the increased detection, treatment and study of both benign and neoplastic prostatic lesions. The advent of aggressive prostate-specific antigen screening and standardization of extended transrectal needle biopsy protocols has resulted in significant stage migration and earlier detection of prostate cancers, a growing proportion of which are lower-volume posterior peripheral zone tumours. Consequently, an increased incidence of anterior-predominant prostate cancers has been observed. Given the histomorphological complexity of the prostate, these developments have necessitated a reconsideration of prostatic anatomy, biopsy strategies in the detection of anterior tumours and the determination and relevance of zonal origin in prostate cancer. This review will provide a contemporary update of these topics, while highlighting specific areas in which a keen understanding of prostatic histoanatomy may influence biopsy interpretation.

Biological significance of perineural invasion (PNI) in prostate cancer

BACKGROUND

In order to better understand the biological significance of perineural invasion (PNI) in prostate cancer, we aimed to analyze in situ the expression of molecules involved in tumor growth or nerve trophicity.

METHODS

Tissues from 66 radical prostatectomies performed for prostate cancer (40 with PNI and 26 without PNI) were selected and included in a tissue microarray (TMA): PNI areas (when available), cancer far from nerves, and nerves far from cancer. The expression of the following molecules was analyzed using immunohistochemistry on TMA slides: macrophage migration inhibitory factor (MIF) and its receptor CD74, EGF receptor (EGFR), heregulin (HRG) and its receptor ErbB3, and the proliferation marker Ki67.

RESULTS

Cancer cells in the PNI areas showed increased proliferation, EGFR and CD74 expression, when compared to cells far from nerves (P = 0.009, 0.0005, and 0.02, respectively). Moreover, cell proliferation and CD74 staining were increased in cancers with PNI features compared to cancers without PNI (P = 0.001), even when adjusting for Gleason score, tumor size, and pathological stage.

CONCLUSIONS

These results suggest that cancer cells in the PNI areas could acquired a growth advantage that could be triggered by the growth factor receptors EGFR and CD74.

[Prognostic role of perineural invasion in prostate biopsy]

INTRODUCTION

Despite tumour cell dissemination through the intraprostatic nervous system being considered as a prostate cancer progression mechanism, the significance of perineural invasion in prostate biopsies to predict extraprostatic extension and its use as a potential prognosis factor is controversial.

MATERIALS AND METHODS

Retrospective study carried out at an institution on 208 patients treated with radical prostatectomy (January 2007 - July 2010) in which the presence of perineural invasion and the Gleason score in the preoperative biopsy were determined, as well as the clinical stage and the pre-surgery PSA. We classified the patients in risk groups in accordance with the D'Amico classification. We performed bivariate and multivariate statistical analyses to establish the correlations between the different variables.

RESULTS

We objectified PNI in 18.3% of the prostate biopsies. 71% of the prostatectomy specimens with perineural invasion presented extraprostatic extension in the previous biopsy against 23.1% when this was not found (p<0.0001) and 47% of the cases showed positive margins with PNI, against 18.3% without perineural invasion (p<0.0001). In fact, in the multivariate analysis, perineural invasion proved to be an independent risk factor in the presentation of extraprostatic extension and positive margins in the prostatectomy specimen.

CONCLUSIONS

The presence of perineural invasion is a useful prognostic factor for predicting extraprostatic extension and the involvement of surgical margin in the radical prostatectomy specimen. We believe that determining it may be a useful tool for improving preoperative diagnosis and planning treatment.

Anatomy and histology of the lower urinary tract

The function of the lower urinary tract is basically storage of urine in the bladder and the at-will periodic evacuation of the stored urine. Urinary incontinence is one of the most common lower urinary tract disorders in adults, but especially in the elderly female. The urethra, its sphincters, and the pelvic floor are key structures in the achievement of continence, but their basic anatomy is little known and, to some extent, still incompletely understood. Because questions with respect to continence arise from human morbidity, but are often investigated in rodent animal models, we present findings in human and rodent anatomy and histology. Differences between males and females in the role that the pelvic floor plays in the maintenance of continence are described. Furthermore, we briefly describe the embryologic origin of ureters, bladder, and urethra, because the developmental origin of structures such as the vesicoureteral junction, the bladder trigone, and the penile urethra are often invoked to explain (clinical) observations. As the human pelvic floor has acquired features in evolution that are typical for a species with bipedal movement, we also compare the pelvic floor of humans with that of rodents to better understand the rodent (or any other quadruped, for that matter) as an experimental model species. The general conclusion is that the "Bauplan" is well conserved, even though its common features are sometimes difficult to discern.

Prostate cancer topography and patterns of lymph node metastasis

Pelvic lymph node (LN) metastasis is a well-recognized route of prostate cancer spread. However, the relationship between topography and the pathologic features of primary prostatic cancers and patterns of pelvic LN metastasis has not been well studied. We reviewed original slides of radical prostatectomies and pelvic LN dissections from 125 patients with LN metastasis and recorded a total number of LN excised/laterality of positive LN, and localization, staging parameters, lymphovascular invasion, and volume of primary tumors.

LN QUANTITY AND DISTRIBUTION

14.6 (mean) and 13 (median) LNs were resected. Seventy-six (61%), 33 (26%), and 16 (13%) cases had 1, 2, and >2 positive LNs; whereas 58, 44, and 20 cases had LN metastasis on the right, left, and bilaterally.

PATHOLOGIC FEATURES

Eighty-six percent (108 of 125) and 37% (46 of 125) of the cases showed extraprostatic extension and seminal vesicle invasion, whereas 64% cases showed lymphovascular invasion. Mean and median total tumor volumes were 6.39 and 3.92 cm, with ≥50% and ≥90% Gleason patterns 4/5 in 105 (84%) and 73 (58%) cases, respectively.

CORRELATION WITH DOMINANT TUMOR LOCATION

Dominant lesions on radical prostatectomy were as follows: 50 right lobe, 44 left lobe, and 31 bilateral lobe tumors. Fifteen of 50 (30%) right lobe and 18 of 44 (41%) left lobe dominant tumors had LN metastasis on the contralateral side. Only 4% (5 of 125) of the cases were associated with anterior dominant tumors.

CONCLUSION

Thirty percent to 40% of LN metastases occurred contralateral to the dominant tumor. LN metastasis is overwhelmingly associated with high-grade, high-stage, and large volume disease. LN positivity is rarely associated with anterior dominant tumors.

Adenocarcinoma of the prostate involving the lumbosacral plexus: MRI evidence to support direct perineural spread

BACKGROUND

Prostate adenocarcinoma, which may recur despite aggressive treatment, has the potential to spread to the lumbosacral plexus. This intraneural involvement is not widely known and is thought to be from direct perineural spread. We hypothesized that high-resolution imaging could provide supportive evidence for this mechanism.

METHODS

The clinical data and imaging studies (magnetic resonance imaging, MRI, and positron emission tomography/computed tomography, PET/CT) of patients evaluated at our institution between 2004 and 2009 for lumbosacral plexopathy due to intraneural prostate carcinoma were retrospectively reviewed.

RESULTS

Four patients presenting with painful lumbosacral plexopathy were found to have intraneural lumbosacral prostate adenocarcinoma. Two patients had involvement of the lumbosacral plexus ipsilateral to the lobe of the prostate most involved with adenocarcinoma at prostatectomy. High-resolution MRI and PET/CT studies revealed similar findings: abnormal soft tissue signal was followed from the prostate (n = 1) or prostatic bed (n = 3) area along the expected course of the pelvic plexus to the level of the sciatic notch, where it involved the sacral spinal nerves and sciatic nerve. Imaging findings were consistent with neoplastic infiltration, which was confirmed at biopsy in three patients.

CONCLUSIONS

The potential for prostate adenocarcinoma to spread to the lumbosacral plexus has, to our knowledge, not been readily appreciated. Because the imaging findings are often subtle, we believe that intraneural lumbosacral plexus involvement may not be uncommon. This study, with the use of high-resolution MRI and PET/CT studies, supports the direct perineural spread of prostate adenocarcinoma via the pelvic plexus to the lumbosacral plexus. This mechanism could also explain cases of leptomeningeal and/or dural-based prostate metastases.

The laminin binding integrin alpha6beta1 in prostate cancer perineural invasion

Metastasizing prostate tumor cells invade along nerves innervating the encapsulated human prostate gland in a process known as perineural invasion. The extracellular matrix laminin class of proteins line the neural route and tumor cells escaping from the gland express the laminin binding integrin alpha6beta1 as a prominent cell surface receptor. Integrin alpha6beta1 promotes aggressive disease and supports prostate tumor cell metastasis to bone. Laminins and their integrin receptors are necessary for the development and maintenance of the peripheral nervous system, indicating the potential role for integrin receptors in directing prostate tumor cell invasion on nerves during perineural invasion.

Cancer-related axonogenesis and neurogenesis in prostate cancer

PURPOSE

Perineural invasion is the only interaction between cancer cells and nerves studied to date. It is a symbiotic relationship between cancer and nerves that results in growth advantage for both. In this article, we present data on a novel biological phenomenon, cancer-related axonogenesis and neurogenesis.

EXPERIMENTAL DESIGN

We identify spatial and temporal associations between increased nerve density and preneoplastic and neoplastic lesions of the human prostate.

RESULTS

Nerve density was increased in cancer areas as well as in preneoplastic lesions compared with controls. Two- and three-dimensional reconstructions of entire prostates confirmed axonogenesis in human tumors. Furthermore, patients with prostate cancer had increased numbers of neurons in their prostatic ganglia compared with controls, corroborating neurogenesis. Finally, two in vitro models confirmed that cancer cells, particularly when interacting with nerves in perineural invasion, induce neurite outgrowth in prostate cancer. Neurogenesis is correlated with features of aggressive prostate cancer and with recurrence in prostate cancer. We also present a putative regulatory mechanism based on semaphorin 4F (S4F). S4F is overexpressed in cancers cells in the perineural in vitro model. Overexpression of S4F in prostate cancer cells induces neurogenesis in the N1E-115 neurogenesis assay and S4F inhibition by small interfering RNA blocks this effect.

CONCLUSIONS

This is the first description of cancer-related neurogenesis and its putative regulatory mechanism.

Association between age and epididymal and accessory sex gland function and their relation to sperm motility

Increased male age has been associated with significant reduction in pregnancy rates. This study investigated the association between age, the function of epididymal and accessory sex glands, and their relation to sperm motility. Ejaculates from 498 men assessed for infertility were analysed according to WHO [1999] guidelines. Seminal markers of epididymal (neutral alpha-glucosidase (NAG)), prostatic (prostate-specific antigen (PSA) and zinc), and seminal vesicle function (fructose) were measured. Four groups according to age were defined: G(21-30) (21-30 years), G(31-40) (31-40 years), G(41-50) (41-50 years), and G(>50) (51-66 years). Percentage progressive motility was significantly lower in G(>50) compared with G(21-30). NAG, PSA, zinc, and fructose were significantly lower in G(>50) compared with G(21-30). In a multiple regression analysis model, NAG and PSA showed positive significant association with percentage progressive motility. The opposite trend was found regarding zinc. No association between fructose and percentage progressive motility was shown. In this cross-sectional study, declined sperm motility observed in men over 50 years of age might be due to age-dependent changes in epididymal and accessory sex gland function.

The prognostic significance of perineural invasion in prostatic cancer biopsies: a systematic review

Men with clinically localized prostate cancer are faced with a wide range of treatment options, and only Gleason grading is universally used as a histopathological prognostic factor for this disease. The significance of perineural invasion in diagnostic biopsies is controversial. Opinion about whether or not it should influence treatment decisions is currently almost equally divided. To address this, the authors performed a systematic review of studies that examine the association between perineural invasion and prostate cancer recurrence. MEDLINE, Embase, and the Web of Knowledge were searched from January 1990 to December 2005. Outcomes analyzed were the development of biochemical or clinical recurrence. Twenty-one articles on the association of perineural invasion in biopsies and prostate cancer recurrence after radical prostatectomy (n = 10) or radiotherapy (n = 11) were found but none on its significance in the context of watchful waiting. Structured data extraction was performed to allow comparisons between articles and to identify sources of heterogeneity to explain discrepancies in results. The considerable variation in study design, execution, and reporting precluded meta-analysis and quantitative risk estimation, but the weight of evidence suggested that perineural invasion in biopsies was a significant prognostic indicator, particularly in specific patient groups defined by presenting serum prostate-specific antigen levels and biopsy Gleason scores. Immediate treatment rather than watchful waiting may be more appropriate for patients with localized prostatic cancer and perineural invasion. However, the data are limited, and well-designed studies that use predefined stringent protocols are required to provide robust estimates of risk to aid in treatment planning.