Periprostatic fat thickness on MRI: correlation with Gleason score in prostate cancer

Periprostatic adipose tissue inhibits tumor progression by secreting apoptotic factors: A natural barrier induced by the immune response during the early stages of prostate cancer

Prostate cancer (PCa) is the second most prevalent malignancy in men worldwide. The risk factors for PCa include obesity, age and family history. Increased visceral fat has been associated with high PCa risk, which has prompted previous researchers to investigate the influence of body composition and fat distribution on PCa prognosis. However, there is a lack of studies focusing on the mechanisms and interactions between periprostatic adipose tissue (PPAT) and PCa cells. The present study investigated the association between the composition of pelvic adipose tissue and PCa aggressiveness to understand the role played by this tissue in PCa progression. Moreover, PPAT-conditioned medium (CM) was prepared to assess the influence of the PPAT secretome on the pathophysiology of PCa. The present study included 50 patients with localized PCa who received robot-assisted radical prostatectomy. Medical records were collected, magnetic resonance imaging scans were analyzed and body compositions were calculated to identify the associations between adipose tissue volume and clinical PCa aggressiveness. In addition, CM was prepared from PPAT and perivesical adipose tissue (PVAT) collected from 25 patients during surgery, and its effects on the PCa cell lines C4-2 and LNCaP, and the prostate epithelial cell line PZ-HPV-7, were investigated using a cell proliferation assay and RNA sequencing (RNA-seq). The results revealed that the initial prostate-specific antigen level was significantly correlated with pelvic and periprostatic adipose tissue volumes. In addition, PPAT volume was significantly higher in patients with extracapsular tumor extension. PCa cell proliferation was significantly reduced when the cells were cultured in PPAT-CM compared with when they were cultured in control- and PVAT-CM. RNA-seq revealed that immune responses, and the cell death and apoptosis pathways were enriched in PPAT-CM-cultured cells indicating that the cytokines or other factors secreted from PPAT-CM induced PCa cell apoptosis. These findings revealed that the PPAT secretome may inhibit PCa cell proliferation by activating immune responses and promoting cancer cell apoptosis. This mechanism may act as a first-line defense during the early stages of PCa.

MRI-measured periprostatic to subcutaneous adipose tissue thickness ratio as an independent risk factor in prostate cancer patients undergoing radical prostatectomy

The purpose of this study is to evaluate whether the periprostatic adipose tissue thickness (PPATT) is an independent prognostic factor for prostate cancer patients after laparoscopic radical prostatectomy (LRP). This retrospective cohort study included consecutive prostate cancer patients who underwent LRP treatment at Wuhan Union Hospital from June 2, 2016, to September 7, 2023. PPATT was defined as the thickness of periprostatic fat and was obtained by measuring the shortest vertical distance from the pubic symphysis to the prostate on the midsagittal T2-weighted MR images. Subcutaneous adipose tissue thickness (SATT) was obtained by measuring the shortest vertical distance from the pubic symphysis to the skin at the same slice with PPATT. The primary outcome of the study was biochemical recurrence (BCR), and the secondary outcome was overall survival (OS). Multivariable Cox regression analysis was used to identify independent prognostic factors for prostate cancer survival and prognosis. Based on the optimal cutoff value, 162 patients were divided into a low PPATT/SATT group (n = 82) and a high PPATT/SATT group (n = 80). During the entire follow-up period (median 23.5 months), 26 patients in the high PPATT/SATT group experienced BCR (32.5%), compared to 18 in the low PPATT/SATT group (22.0%). Kaplan-Meier curve analysis indicated that the interval to BCR was significantly shorter in the high PPATT/SATT group (P = 0.037). Multivariable Cox regression analysis revealed that an increase in the PPATT/SATT ratio was associated with BCR (hazard ratio: 1.90, 95% CI, 1.03-3.51; P = 0.040). The PPATT/SATT ratio is a significant independent risk factor for BCR after LRP for prostate cancer patients.

Tumoral periprostatic adipose tissue exovesicles-derived miR-20a-5p regulates prostate cancer cell proliferation and inflammation through the RORA gene

BACKGROUND

From the first steps of prostate cancer (PCa) initiation, tumours are in contact with the most-proximal adipose tissue called periprostatic adipose tissue (PPAT). Extracellular vesicles are important carriers of non-coding RNA such as miRNAs that are crucial for cellular communication. The secretion of extracellular vesicles by PPAT may play a key role in the interactions between adipocytes and tumour. Analysing the PPAT exovesicles (EVs) derived-miRNA content can be of great relevance for understanding tumour progression and aggressiveness.

METHODS

A total of 24 samples of human PPAT and 17 samples of perivesical adipose tissue (PVAT) were used. EVs were characterized by western blot and transmission electron microscopy (TEM), and uptake by PCa cells was verified by confocal microscopy. PPAT and PVAT explants were cultured overnight, EVs were isolated, and miRNA content expression profile was analysed. Pathway and functional enrichment analyses were performed seeking potential miRNA targets. In vitro functional studies were evaluated using PCa cells lines, miRNA inhibitors and target gene silencers.

RESULTS

Western blot and TEM revealed the characteristics of EVs derived from PPAT (PPAT-EVs) samples. The EVs were up taken and found in the cytoplasm of PCa cells. Nine miRNAs were differentially expressed between PPAT and PVAT samples. The RORA gene (RAR Related Orphan Receptor A) was identified as a common target of 9 miRNA-regulated pathways. In vitro functional analysis revealed that the RORA gene was regulated by PPAT-EVs-derived miRNAs and was found to be implicated in cell proliferation and inflammation.

CONCLUSION

Tumour periprostatic adipose tissue is linked to PCa tumour aggressiveness and could be envisaged for new therapeutic strategies.

Measurements of peri-prostatic adipose tissue by MRI predict bone metastasis in patients with newly diagnosed prostate cancer

Objectives

To investigate the role of MRI measurements of peri-prostatic adipose tissue (PPAT) in predicting bone metastasis (BM) in patients with newly diagnosed prostate cancer (PCa).

Methods

We performed a retrospective study on 156 patients newly diagnosed with PCa by prostate biopsy between October 2010 and November 2022. Clinicopathologic characteristics were collected. Measurements including PPAT volume and prostate volume were calculated by MRI, and the normalized PPAT (PPAT volume/prostate volume) was computed. Independent predictors of BM were determined by univariate and multivariate logistic regression analysis, and a new nomogram was developed based on the predictors. Receiver operating characteristic (ROC) curves were used to estimate predictive performance.

Results

PPAT and normalized PPAT were associated with BM (P<0.001). Normalized PPAT positively correlated with clinical T stage(cT), clinical N stage(cN), and Grading Groups(P<0.05). The results of ROC curves indicated that PPAT and normalized PPAT had promising predictive value for BM with the AUC of 0.684 and 0.775 respectively. Univariate and multivariate analysis revealed that high normalized PPAT, cN, and alkaline phosphatase(ALP) were independently predictors of BM. The nomogram was developed and the concordance index(C-index) was 0.856.

Conclusions

Normalized PPAT is an independent predictor for BM among with cN, and ALP. Normalized PPAT may help predict BM in patients with newly diagnosed prostate cancer, thus providing adjunctive information for BM risk stratification and bone scan selection.

Genetic ancestry and radical prostatectomy findings in Hispanic/Latino patients

Background

African ancestry is a known factor associated with the presentation and aggressiveness of prostate cancer (PC). Hispanic/Latino populations exhibit varying degrees of genetic admixture across Latin American countries, leading to diverse levels of African ancestry. However, it remains unclear whether genetic ancestry plays a role in the aggressiveness of PC in Hispanic/Latino patients. We explored the associations between genetic ancestry and the clinicopathological data in Hispanic/Latino PC patients from Colombia.

Patients and methods

We estimated the European, Indigenous and African genetic ancestry, of 230 Colombian patients with localized/regionally advanced PC through a validated panel for genotypification of 106 Ancestry Informative Markers. We examined the associations of the genetic ancestry components with the Gleason Grade Groups (GG) and the clinicopathological characteristics.

Results

No association was observed between the genetic ancestry with the biochemical recurrence or Gleason GG; however, in a two groups comparison, there were statistically significant differences between GG3 and GG4/GG5 for European ancestry, with a higher mean ancestry proportion in GG4/GG5. A lower risk of being diagnosed at an advanced age was observed for patients with high African ancestry than those with low African ancestry patients (OR: 0.96, CI: 0.92-0.99, p=0.03).

Conclusion

Our findings revealed an increased risk of presentation of PC at an earlier age in patients with higher African ancestry compared to patients with lower African ancestry in our Hispanic/Latino patients.

Variable effects of periprostatic adipose tissue on prostate cancer cells: Role of adipose tissue lipid composition and cancer cells related factors

BACKGROUND

Periprostatic adipose tissue (PPAT) is likely to modulate prostate cancer (PCa) progression. We analyzed the variations in the effect of PPAT on cancer cells, according to its fatty acid (FA) composition and tumor characteristics.

METHODS

The expression of markers of aggressiveness Ki67 and Zeb1, and epigenetic marks that could be modified during PCa progression, was analyzed by immunohistochemistry on a tissue-micro-array containing 59 pT3 PCa, including intra-prostatic areas and extra-prostatic foci in contact with PPAT belonging to the same tumor. In addition, we cocultivated PC3 and LNCaP cell lines with PPAT, which were then analyzed for FA composition.

RESULTS

Although the contact between PPAT and cancer cells led overall to an increase in Ki67 and Zeb1, and a decrease in the epigenetic marks 5MC, 5HMC, and H3K27ac, these effects were highly heterogeneous. Increased proliferation in extra-prostatic areas was associated with the international society of uropathology score. PC3 and LNCaP cocultures with PPAT led to increased Ki67, Zeb1 and H3K27me3, but only for PPAT associated with aggressive PCa. PC3 proliferation was correlated with high 20.2 n-6 and low 20.5n-3 in PPAT.

CONCLUSIONS

These results suggest that the effects of PPAT on cancer cells may depend on both PCa characteristics and PPAT composition, and could lead to propose nutritional supplementation.

A modified U-Net convolutional neural network for segmenting periprostatic adipose tissue based on contour feature learning

Objective

This study trains a U-shaped fully convolutional neural network (U-Net) model based on peripheral contour measures to achieve rapid, accurate, automated identification and segmentation of periprostatic adipose tissue (PPAT).

Methods

Currently, no studies are using deep learning methods to discriminate and segment periprostatic adipose tissue. This paper proposes a novel and modified, U-shaped convolutional neural network contour control points on a small number of datasets of MRI T2W images of PPAT combined with its gradient images as a feature learning method to reduce feature ambiguity caused by the differences in PPAT contours of different patients. This paper adopts a supervised learning method on the labeled dataset, combining the probability and spatial distribution of control points, and proposes a weighted loss function to optimize the neural network's convergence speed and detection performance. Based on high-precision detection of control points, this paper uses a convex curve fitting to obtain the final PPAT contour. The imaging segmentation results were compared with those of a fully convolutional network (FCN), U-Net, and semantic segmentation convolutional network (SegNet) on three evaluation metrics: Dice similarity coefficient (DSC), Hausdorff distance (HD), and intersection over union ratio (IoU).

Results

Cropped images with a 270 × 270-pixel matrix had DSC, HD, and IoU values of 70.1%, 27 mm, and 56.1%, respectively; downscaled images with a 256 × 256-pixel matrix had 68.7%, 26.7 mm, and 54.1%. A U-Net network based on peripheral contour characteristics predicted the complete periprostatic adipose tissue contours on T2W images at different levels. FCN, U-Net, and SegNet could not completely predict them.

Conclusion

This U-Net convolutional neural network based on peripheral contour features can identify and segment periprostatic adipose tissue quite well. Cropped images with a 270 × 270-pixel matrix are more appropriate for use with the U-Net convolutional neural network based on contour features; reducing the resolution of the original image will lower the accuracy of the U-Net convolutional neural network. FCN and SegNet are not appropriate for identifying PPAT on T2 sequence MR images. Our method can automatically segment PPAT rapidly and accurately, laying a foundation for PPAT image analysis.

The importance of periprostatic fat tissue thickness measured by preoperative multiparametric magnetic resonance imaging in upstage prediction after robot-assisted radical prostatectomy

PURPOSE

We analyzed the surgical results of patients who were treated and followed up for prostate cancer in our clinic to predict the relationship between periprostatic adipose tissue and patients with and without pathologically upstaged disease.

MATERIALS AND METHODS

The study included patients who had undergone robot-assisted radical prostatectomy and preoperative multiparametric prostate magnetic resonance imaging between 18 February 2019 and 1 April 2022. The patients were divided into two groups, and the surgical and transrectal ultrasound-guided biopsy pathology results were compared according to tumor grade and distribution in 124 patients who met the selection criteria. We analyzed the relationships between upgrading/upstaging and periprostatic adipose tissue thickness (PPATT) and subcutaneous adipose tissue thickness (SATT) as measured in magnetic resonance imaging.

RESULTS

The median PPATT was 4.03 mm, whereas the median SATT was 36.4 mm. Upgrading was detected in 45 patients (36.3%), and upstaging was detected in 42 patients (33.9%). A receiver operating characteristic regression analysis revealed that a PPATT >3 mm was a predictive factor for upstaging after radical prostatectomy (area under curve=0.623, 95% confidence interval [CI] 0.519-0.727, p=0.025). Multivariate logistic regression analyses revealed that prostate specific antigen density ≥0.15 ng/mL/cm3 (odds ratio [OR] 5.054, 95% CI 2.008-12.724, p=0.001), International Society of Urological Pathology grade ≥4 (OR 9.369, 95% CI 2.109-21.626, p=0.003) and higher PPATT (OR 1.358, 95% CI 1.081-1.707, p=0.009) were independent risk factors for upstaging after radical prostatectomy.

CONCLUSIONS

We believe that the PPATT may be a predictive indicator for upstaging after robot-assisted laparoscopic radical prostatectomy.

Exploring the role of the inflammasomes on prostate cancer: Interplay with obesity

Obesity is a weight-related disorder characterized by excessive adipose tissue growth and dysfunction which leads to the onset of a systemic chronic low-grade inflammatory state. Likewise, inflammation is considered a classic cancer hallmark affecting several steps of carcinogenesis and tumor progression. In this regard, novel molecular complexes termed inflammasomes have been identified which are able to react to a wide spectrum of insults, impacting several metabolic-related disorders, but their contribution to cancer biology remains unclear. In this context, prostate cancer (PCa) has a markedly inflammatory component, and patients frequently are elderly individuals who exhibit weight-related disorders, being obesity the most prevalent condition. Therefore, inflammation, and specifically, inflammasome complexes, could be crucial players in the interplay between PCa and metabolic disorders. In this review, we will: 1) discuss the potential role of each inflammasome component (sensor, molecular adaptor, and targets) in PCa pathophysiology, placing special emphasis on IL-1β/NF-kB pathway and ROS and hypoxia influence; 2) explore the association between inflammasomes and obesity, and how these molecular complexes could act as the cornerstone between the obesity and PCa; and, 3) compile current clinical trials regarding inflammasome targeting, providing some insights about their potential use in the clinical practice.

MRI-measured adipose features as predictive factors for detection of prostate cancer in males undergoing systematic prostate biopsy: a retrospective study based on a Chinese population

In this study, we retrospectively evaluated the data of 901 men undergoing ultrasonography-guided systematic prostate biopsy between March 2013 and May 2022. Adipose features, including periprostatic adipose tissue (PPAT) thickness and subcutaneous fat thickness, were measured using MRI before biopsy. Prediction models of all PCa and clinically significant PCa (csPCa) (Gleason score higher than 6) were established based on variables selected by multivariate logistic regression and prediction nomograms were constructed. Patients with PCa had higher PPAT thickness (4.64 [3.65-5.86] vs. 3.54 [2.49-4.51] mm, p < 0.001) and subcutaneous fat thickness (29.19 [23.05-35.95] vs. 27.90 [21.43-33.93] mm, p = 0.013) than those without PCa. Patients with csPCa had higher PPAT thickness (4.78 [3.80-5.88] vs. 4.52 [3.80-5.63] mm, p = 0.041) than those with non-csPCa. Adding adipose features to the prediction models significantly increased the area under the receiver operating characteristics curve for the prediction of all PCa (0.850 vs. 0.819, p < 0.001) and csPCa (0.827 vs. 0.798, p < 0.001). Based on MRI-measured adipose features and clinical parameters, we established two nomograms that were simple to use and could improve patient selection for prostate biopsy in Chinese population.

Obesity-Related Cross-Talk between Prostate Cancer and Peripheral Fat: Potential Role of Exosomes

The molecular mechanisms of obesity-induced cancer progression have been extensively explored because of the significant increase in obesity and obesity-related diseases worldwide. Studies have shown that obesity is associated with certain features of prostate cancer. In particular, bioactive factors released from periprostatic adipose tissues mediate the bidirectional communication between periprostatic adipose tissue and prostate cancer. Moreover, recent studies have shown that extracellular vesicles have a role in the relationship between tumor peripheral adipose tissue and cancer progression. Therefore, it is necessary to investigate the feedback mechanisms between prostate cancer and periglandular adipose and the role of exosomes as mediators of signal exchange to understand obesity as a risk factor for prostate cancer. This review summarizes the two-way communication between prostate cancer and periglandular adipose and discusses the potential role of exosomes as a cross-talk and the prospect of using adipose tissue as a means to obtain exosomes in vitro. Therefore, this review may provide new directions for the treatment of obesity to suppress prostate cancer.

Body composition and pelvic fat distribution are associated with prostate cancer aggressiveness and can predict biochemical recurrence

This study evaluated the effect of body composition and pelvic fat distribution on the aggressiveness and prognosis of localized prostate cancer. This study included patients who underwent robot-assisted radical prostatectomy with positive surgical margins. Clinicodemographic data were collected from patients' medical reports. Pretreatment magnetic resonance images (MRI) obtained for cancer staging were reviewed by a single radiologist to calculate pelvic fat distribution and body composition. We correlated these body composition parameters with initial prostate-specific antigen (iPSA), Gleason score, extracapsular tumor extension, and biochemical recurrence (BCR)-free survival. The iPSA was significantly associated with body mass index (BMI; P = .027), pelvic fat volume (P = .004), and perirectal fat volume (P = .001), whereas the Gleason score was significantly associated with BMI only (P = .011). Tumor extracapsular extension was significantly associated with increased periprostatic fat volume (P = .047). Patients with less subcutaneous fat thickness (<2.4 cm) had significantly poor BCR-free survival (P = .039). Pelvic fat distribution, including pelvic fat volume, perirectal fat volume, and periprostatic fat volume, were significantly correlated with prostate cancer aggressiveness. Patients with less subcutaneous fat had an increased risk of BCR after radical prostatectomy.

Interplay between Prostate Cancer and Adipose Microenvironment: A Complex and Flexible Scenario

Adipose tissue is part of the prostate cancer (PCa) microenvironment not only in the periprostatic area, but also in the most frequent metastatic sites, such as bone marrow and pelvic lymph nodes. The involvement of periprostatic adipose tissue (PPAT) in the aggressiveness of PCa is strongly suggested by numerous studies. Many molecules play a role in the reciprocal interaction between adipocytes and PCa cells, including adipokines, hormones, lipids, and also lipophilic pollutants stored in adipocytes. The crosstalk has consequences not only on cancer cell growth and metastatic potential, but also on adipocytes. Although most of the molecules released by PPAT are likely to promote tumor growth and the migration of cancer cells, others, such as the adipokine adiponectin and the n-6 or n-3 polyunsaturated fatty acids (PUFAs), have been shown to have anti-tumor properties. The effects of PPAT on PCa cells might therefore depend on the balance between the pro- and anti-tumor components of PPAT. In addition, genetic and environmental factors involved in the risk and/or aggressiveness of PCa, including obesity and diet, are able to modulate the interactions between PPAT and cancer cells and their consequences on the growth and the metastatic potential of PCa.

Thromboinflammatory Processes at the Nexus of Metabolic Dysfunction and Prostate Cancer: The Emerging Role of Periprostatic Adipose Tissue

Simple Summary

As overweight and obesity increase among the population worldwide, a parallel increase in the number of individuals diagnosed with prostate cancer was observed. There appears to be a relationship between both diseases where the increase in the mass of fat tissue can lead to inflammation. Such a state of inflammation could produce many factors that increase the aggressiveness of prostate cancer, especially if this inflammation occurred in the fat stores adjacent to the prostate. Another important observation that links obesity, fat tissue inflammation, and prostate cancer is the increased production of blood clotting factors. In this article, we attempt to explain the role of these latter factors in the effect of increased body weight on the progression of prostate cancer and propose new ways of treatment that act by affecting how these clotting factors work.

Abstract

The increased global prevalence of metabolic disorders including obesity, insulin resistance, metabolic syndrome and diabetes is mirrored by an increased incidence of prostate cancer (PCa). Ample evidence suggests that these metabolic disorders, being characterized by adipose tissue (AT) expansion and inflammation, not only present as risk factors for the development of PCa, but also drive its increased aggressiveness, enhanced progression, and metastasis. Despite the emerging molecular mechanisms linking AT dysfunction to the various hallmarks of PCa, thromboinflammatory processes implicated in the crosstalk between these diseases have not been thoroughly investigated. This is of particular importance as both diseases present states of hypercoagulability. Accumulating evidence implicates tissue factor, thrombin, and active factor X as well as other players of the coagulation cascade in the pathophysiological processes driving cancer development and progression. In this regard, it becomes pivotal to elucidate the thromboinflammatory processes occurring in the periprostatic adipose tissue (PPAT), a fundamental microenvironmental niche of the prostate. Here, we highlight key findings linking thromboinflammation and the pleiotropic effects of coagulation factors and their inhibitors in metabolic diseases, PCa, and their crosstalk. We also propose several novel therapeutic targets and therapeutic interventions possibly modulating the interaction between these pathological states.

Fatty Acid Metabolism Reprogramming in Advanced Prostate Cancer

Prostate cancer (PCa) is a carcinoma in which fatty acids are abundant. Fatty acid metabolism is rewired during PCa development. Although PCa can be treated with hormone therapy, after prolonged treatment, castration-resistant prostate cancer can develop and can lead to increased mortality. Changes to fatty acid metabolism occur systemically and locally in prostate cancer patients, and understanding these changes may lead to individualized treatments, especially in advanced, castration-resistant prostate cancers. The fatty acid metabolic changes are not merely reflective of oncogenic activity, but in many cases, these represent a critical factor in cancer initiation and development. In this review, we analyzed the literature regarding systemic changes to fatty acid metabolism in PCa patients and how these changes relate to obesity, diet, circulating metabolites, and peri-prostatic adipose tissue. We also analyzed cellular fatty acid metabolism in prostate cancer, including fatty acid uptake, de novo lipogenesis, fatty acid elongation, and oxidation. This review broadens our view of fatty acid switches in PCa and presents potential candidates for PCa treatment and diagnosis.

Increased Body Mass Index Is a Risk Factor for Poor Clinical Outcomes after Radical Prostatectomy in Men with International Society of Urological Pathology Grade Group 1 Prostate Cancer Diagnosed with Systematic Biopsies

INTRODUCTION

The association between obesity and clinically significant prostate cancer (PCa) is still a matter of debate. In this study, we evaluated the effect of body mass index (BMI) on the prediction of pathological unfavorable disease (UD), positive surgical margins (PSMs), and biochemical recurrence (BCR) in patients with clinically localized (≤cT2c) International Society of Urological Pathology (ISUP) grade group 1 PCa at biopsy.

METHODS

427 patients with ISUP grade group 1 PCa who have undergone radical prostatectomy and BMI evaluation were included. The outcome of interest was the presence of UD (defined as ISUP grade group ≥3 and pT ≥3a), PSM, and BCR.

RESULTS

Statistically significant differences resulted in comparing BMI with prostate-specific antigen (PSA) and serum testosterone levels (both p < 0.0001). Patients with UD and PSM had higher BMI values (p < 0.0001 and p = 0.006, respectively). BCR-free survival was significantly decreased in patients with higher BMI values (p < 0.0001). BMI was an independent risk factor for BCR and PSM. Receiver-operating characteristic analysis testing PSA accuracy in different BMI groups, showed that PSA had a reduced predictive value (area under the curve [AUC] = 0.535; 95% confidence interval [CI] = 0.422-0.646), in obese men compared to overweight (AUC = 0.664; 95% CI = 0.598-0.725) and normal weight patients (AUC = 0.721; 95% CI = 0.660-0.777).

CONCLUSION

Our findings show that increased BMI is a significant predictor of UD and PSM at RP in patients with preoperative low-to intermediate-risk diseases, suggesting that BMI evaluation may be useful in a clinical setting to identify patients with favorable preoperative disease characteristics harboring high-risk PCa.

Mechanistic Insights into the Link between Obesity and Prostate Cancer

Obesity is a pandemic of increasing worldwide prevalence. There is evidence of an association between obesity and the risk of prostate cancer from observational studies, and different biologic mechanisms have been proposed. The chronic low-level inflammation within the adipose tissue in obesity results in oxidative stress, activation of inflammatory cytokines, deregulation of adipokines signaling, and increased circulating levels of insulin and insulin-like growth factors (IGF). These mechanisms may be involved in epithelial to mesenchymal transformation into a malignant phenotype that promotes invasiveness, aggressiveness, and metastatic potential of prostate cancer. A thorough understanding of these mechanisms may be valuable in the development of effective prostate cancer prevention strategies and treatments. This review provides an overview of these mechanisms.

Peri-prostatic adipose tissue measurements using MRI predict prostate cancer aggressiveness in men undergoing radical prostatectomy

OBJECTIVES

To evaluate the effect of peri-prostatic adipose tissue (PPAT) measurements using preoperative MRI on the prediction of prostate cancer (PCa) aggressiveness in men undergoing radical prostatectomy (RP).

METHODS

We performed a retrospective study on 179 consecutive patients receiving RP from June 2016 to October 2018. Clinical characteristics were collected. PPAT measurements including peri-prostatic fat area (PPFA) and peri-prostatic fat area to prostate area (PA) ratio (PPFA/PA) were calculated by MRI. Multivariable logistic regression analysis was performed to identify independent predictors of PCa lymph node metastasis (LNM). The predictive performance was estimated through ROC curves. Nomograms were created based on the predictors.

RESULTS

Pathologic Gleason score positively correlated with digital rectal examination (DRE), PSA, PPFA/PA, P504S, and Ki-67 (all P < 0.05). ROC curves revealed that high PPFA and high PPFA/PA were associated with LNM (both P < 0.05). Multivariate analysis revealed that high PPFA/PA, pathologic Gleason score, pT stage, and Ki-67 were independently predictive of LNM. The nomograms were created and the C-index was 0.945.

CONCLUSIONS

PPFA/PA is an independent predictor for LNM along with Gleason score, pT stage, and Ki-67. PPFA/PA may help predict LNM in men undergoing RP, thus providing adjunctive information for therapeutic strategy and prognosis.

Periprostatic fat thickness measured on MRI correlates with lower urinary tract symptoms, erectile function, and benign prostatic hyperplasia progression

This study investigated the correlation between periprostatic fat thickness (PPFT) measured on magnetic resonance imaging and lower urinary tract symptoms, erectile function, and benign prostatic hyperplasia (BPH) progression. A total of 286 treatment-naive men diagnosed with BPH in our department between March 2017 and February 2019 were included. Patients were divided into two groups according to the median value of PPFT: high (PPFT >4.35 mm) PPFT group and low (PPFT <4.35 mm) PPFT group. After the initial evaluation, all patients received a combination drug treatment of tamsulosin and finasteride for 12 months. Of the 286 enrolled patients, 244 completed the drug treatment course. Patients with high PPFT had larger prostate volume (PV; P = 0.013), higher International Prostate Symptom Score (IPSS; P = 0.008), and lower five-item version of the International Index of Erectile Function (IIEF-5) score (P = 0.002) than those with low PPFT. Both high and low PPFT groups showed significant improvements in PV, maximum flow rate, IPSS, and quality of life score and a decrease of IIEF-5 score after the combination drug treatment. The decrease of IIEF-5 score was more obvious in the high PPFT group than that in the low PPFT group. In addition, more patients in the high PPFT group underwent prostate surgery than those in the low PPFT group. Moreover, Pearson's correlation coefficient analysis indicated that PPFT was positively correlated with age, PV, and IPSS and negatively correlated with IIEF-5 score; however, body mass index was only negatively correlated with IIEF-5 score.

Prognostic Value of CT-Attenuation and 18F-Fluorodeoxyglucose Uptake of Periprostatic Adipose Tissue in Patients with Prostate Cancer

This study aimed to assess the prognostic value of computed tomography (CT)-attenuation and ¹⁸F-fluorodeoxyglucose (FDG) uptake of periprostatic adipose tissue (PPAT) for predicting disease progression-free survival (DPFS) in patients with prostate cancer. Seventy-seven patients with prostate cancer who underwent staging FDG positron emission tomography (PET)/CT were retrospectively reviewed. CT-attenuation (HU) and FDG uptake (SUV) of PPAT were measured from the PET/CT images. The relationships between these PPAT parameters and clinical factors were assessed, and a Cox proportional hazard regression test was performed to evaluate the prognostic significance of PPAT HU and SUV. PPAT HU and SUV showed significant positive correlations with tumor stage and serum prostate-specific antigen level (PSA) (p < 0.05). Patients with high PPAT HU and SUV had significantly worse DPFS than those with low PPAT HU and SUV (p < 0.05). In multivariate analysis, PPAT SUV was a significant predictor of DPFS after adjusting for tumor stage, serum PSA, and tumor SUV (p = 0.003; hazard ratio, 1.50; 95% confidence interval, 1.15–1.96). CT-attenuation and FDG uptake of PPAT showed significant association with disease progression in patients with prostate cancer. These imaging findings may be evidence of the role of PPAT in prostate cancer progression.

Assessment of Periprostatic and Subcutaneous Adipose Tissue Lipolysis and Adipocyte Size from Men with Localized Prostate Cancer

The prostate is surrounded by periprostatic adipose tissue (PPAT), the thickness of which has been associated with more aggressive prostate cancer (PCa). There are limited data regarding the functional characteristics of PPAT, how it compares to subcutaneous adipose tissue (SAT), and whether in a setting of localized PCa, these traits are altered by obesity or disease aggressiveness. PPAT and SAT were collected from 60 men (age: 42–78 years, BMI: 21.3–35.6 kg/m²) undergoing total prostatectomy for PCa. Compared to SAT, adipocytes in PPAT were smaller, had the same basal rates of fatty acid release (lipolysis) yet released less polyunsaturated fatty acid species, and were more sensitive to isoproterenol-stimulated lipolysis. Basal lipolysis of PPAT was increased in men diagnosed with less aggressive PCa (Gleason score (GS) ≤ 3 + 4) compared to men with more aggressive PCa (GS ≥ 4 + 3) but no other measured adipocyte parameters related to PCa aggressiveness. Likewise, there was no difference in PPAT lipid biology between lean and obese men. In conclusion, lipid biological features of PPAT do differ from SAT; however, we did not observe any meaningful difference in ex vivo PPAT biology that is associated with PCa aggressiveness or obesity. As such, our findings do not support a relationship between altered PCa behavior in obese men and the metabolic reprogramming of PPAT.

Supplemental estrogen and caloric restriction reduce obesity-induced periprostatic white adipose inflammation in mice

Obesity is associated with an increased incidence of high-grade prostate cancer (PC) and worse prognosis for PC patients. Recently, we showed in men that obesity-related periprostatic white adipose tissue (WAT) inflammation, characterized by macrophages surrounding dead or dying adipocytes forming crown-like structures, was associated with high-grade PC. Possibly, interventions that suppress periprostatic WAT inflammation will improve outcomes for men with PC. Here, we tested the hypothesis that supplemental 17β-estradiol (E2) could decrease periprostatic WAT inflammation in obese male mice. Mice were fed a high-fat diet to induce periprostatic WAT inflammation before being treated with supplemental E2. E2 supplementation suppressed caloric intake, induced weight loss, decreased periprostatic WAT inflammation and downregulated the expression of genes linked to inflammation including Cd68, Mcp1 and Tnf. Similar to the effects of E2 supplementation, treatment with diethylstilbestrol, a synthetic estrogen, also suppressed caloric intake and reduced periprostatic WAT inflammation. To determine whether the observed effects of supplemental estrogen could be reproduced by caloric restriction (CR) alone, obese mice were put on a 30% CR diet. Like estrogen treatment, CR was effective in reducing body weight, periprostatic WAT inflammation and the expression of pro-inflammatory genes. Transcriptomic analyses of periprostatic fat showed that obesity was associated with enrichment in inflammatory response pathways, which were normalized by both supplemental E2 and CR. Taken together, these findings strengthen the rationale for future efforts to determine whether either CR or supplemental estrogen will decrease periprostatic WAT inflammation and thereby improve outcomes for men with PC.

Impact of peri-prostatic fat measurements using MRI on the prediction of prostate cancer with transrectal ultrasound-guided biopsy

OBJECTIVES

To estimate the impact of peri-prostatic fat (PPF) measurements using preoperative magnetic resonance imaging on the prediction of prostate cancer (PCa) with transrectal ultrasound-guided biopsy.

PATIENTS AND METHODS

We performed a retrospective 2-center study on 660 consecutive patients receiving transrectal ultrasound-guided biopsy-biopsy from June 2016 to October 2018. Pathologic and immunohistochemical characteristics were collected. PPF measurements including PPF area (PPFA) and PPFA to prostate area (PA) ratio (PPFA/PA) were assessed by preoperative staging magnetic resonance imaging. Clinical variables were correlated with Gleason score by using Spearman (ρ) correlation coefficients. Multivariable analysis was performed to identify independent predictors of PCa. The diagnostic performance was estimated using ROC curves.

RESULTS

The Gleason score was significantly correlated with age (ρ = 0.114, P = 0.035), prostate-specific antigen (PSA) (ρ = 0.482, P < 0.001), PIRADS scoring (ρ = 0.403, P < 0.001) and PPFA/PA (ρ = 0.238, P < 0.001). Multivariate analysis revealed that PPFA/PA, age, digital rectal examination, family history of PCa, PSA, and PIRADS scoring were independently predictive of PCa. The ROC AUC to detect PCa or clinically significant PCa (CS-PCa; Gleason Score 3 + 4 or greater) improved with the addition of PPFA/PA (PCa: 0.93 vs. 0.89; CS-PCa: 0.92 vs. 0.90).

CONCLUSION

PPFA/PA is an independent predictor for PCa along with age, digital rectal examination, family history of PCa, PSA, and PIRADS scoring. PPF measurements especially PPFA/PA may help detect PCa or CS-PCa, thus helping improve PCa risk stratification and screening to avoid unnecessary biopsies.

Pre-treatment ratio of periprostatic to subcutaneous fat thickness on MRI is an independent survival predictor in hormone-naïve men with advanced prostate cancer

BACKGROUND

Epidemiological studies have shown an association between obesity and prostate cancer (PCa) aggressiveness. However, little is known about periprostatic fat (PPF) and its relationship with overall fat deposition in PCa. PPF is thought to contribute to PCa growth and migration via secreted factors and induction of chronic inflammation. We investigated if pre-treatment PPF thickness correlates with overall survival (OS).

METHODS

We reviewed 85 hormone-naïve men with advanced PCa who had received androgen deprivation therapy (ADT). PPF thickness was measured by magnetic resonance imaging (MRI) and compared with subcutaneous fat (SCF) thickness as an internal control. Visceral fat (VF) area measured by computed tomography served as an additional control. We evaluated the relationship between laboratory data, pathology results, and obesity parameters and OS.

RESULTS

Median follow-up was 50.6 months. Thirty-six patients died during follow-up. Univariate analysis revealed that nadir PSA titer, Gleason score, N stage, M stage, extent of disease by bone scan grade, hemoglobin, lactate dehydrogenase, alkaline phosphatase, and PPF/SCF ratio were associated with OS. Multivariate analysis revealed that nadir PSA titer, N stage, and PPF/SCF ratio were independent prognostic factors for survival. The 5-year OS in the patients with higher PPF/SCF ratio (≥ 1) and lower PPF/SCF ratio (< 1) was 49.5% and 66.5%, respectively (P = 0.039).

CONCLUSIONS

Pre-treatment ratio of PPF-to-SCF thickness on MRI is an independent predictor of survival in hormone-naïve men with advanced PCa. This could be useful for predicting which patients are more likely to develop castration-resistant PCa.

Periprostatic Fat Thickness on MRI is an Independent Predictor of Time to Castration-resistant Prostate Cancer in Chinese Patients With Newly Diagnosed Prostate Cancer Treated With Androgen Deprivation Therapy

BACKGROUND

The aim of this study was to evaluate the association between periprostatic fat thickness (PPFT) and time to castration-resistant prostate cancer (CRPC) in newly diagnosed patients with prostate cancer (PCa) treated with androgen deprivation therapy (ADT).

PATIENTS AND METHODS

We retrospectively reviewed the medical records of 150 patients with PCa treated with ADT at our hospital between June 2011 and June 2017. PPFT measured on magnetic resonance imaging (MRI) and PPFT/periprostatic fat volume (PPFV) measured on computed tomography (CT) were evaluated. Kaplan-Meier curves and log-rank tests were used to assess significant differences in time to CRPC between the 2 groups (high PPFT vs. low PPFT, determined by PPFT > or < the median value, respectively). Univariable and multivariable Cox regression analyses were employed to identify the potential prognostic factors for survival.

RESULTS

The median value of PPFT measured on MRI was 0.555 cm. PPFT was significantly associated with PPFV measured on CT images (with a correlation coefficient of 0.825; P < .001). A total of 66 patients (44%) progressed to CRPC during the follow-up period. Patients with high PPFT (measured on MRI) showed a significantly shorter PFS than patients with low PPFT. Multivariable Cox analysis demonstrated that T stage, presence of distant metastasis, shorter time to prostate-specific antigen nadir, higher prostate-specific antigen nadir, Gleason score (greater than 4 + 4), and high PPFT were significantly associated with shorter PFS.

CONCLUSIONS

PPFT is significantly associated with PPFV measured on CT images. PPFT measured on MRI is a readily available and significant predictor of time to CRPC in patients with PCa receiving ADT as the primary treatment.

Metabolomic profiling for the identification of novel diagnostic markers and therapeutic targets in prostate cancer: an update

INTRODUCTION

An altered metabolic regulation is involved in the development and progression of different cancer types. As well as this, many genes associated with tumors are shown to have an important role in control of the metabolism. The incidence of prostate cancer (PCa) is increased in men with metabolic disorders. In particular, obesity is an established risk factor for PCa. An increased body mass index correlates with aggressive disease, and a higher risk of biochemical recurrence and prostate cancer-specific mortality. Increased lipogenesis is also one of the most significant events in PCa metabolism reprogramming. Areas covered: In this article, we provide an updated review of the current understanding of the PCa metabolome and evaluate the possibility of unveiling novel therapeutic targets. Expert opinion: Obesity is an established risk factor for PCa, and an increased BMI correlates with aggressive disease, and a higher risk of biochemical recurrence and prostate cancer-specific mortality. PCa metabolome is characterized by the accumulation of metabolic intermediates and an increased expression of genes in the tricarboxylic acid cycle, the induction of de novo lipogenesis and cholesterogenesis. PCa cells can induce different alterations in their microenvironment by modulating the crosstalk between cancer and stromal cells.

Periprostatic fat adipokine expression is correlated with prostate cancer aggressiveness in men undergoing radical prostatectomy for clinically localized disease

OBJECTIVES

To investigate the relationship between periprostatic adipose tissue (PPAT) adipokine expression and prostate cancer (PCa) aggressiveness using both pathological features of radical prostatectomy (RP) and multiparametric magnetic resonance imaging ( MRI) variables.

PATIENTS AND METHODS

Sixty-nine men were recruited to assess immunohistochemical expression of tumour necrosis factor (TNF)α and vascular endothelial growth factor (VEGF) of periprostatic fat of RP specimens. Per cent immunopositivity was quantified on scanned slides using the Aperio Positive Pixel Count algorithm for PPAT TNFα, VEGF and androgen receptors. Periprostatic fat volume (PFV) was segmented on contiguous T₁ -weighted axial MRI slices from the level of the prostate base to apex. PFV was normalized to prostate volume (PV) to account for variations in PV (normalized PFV = PFV/PV). MRI quantitative values (K_ep , K_trans and apparent diffusion coefficient) were measured from the PCa primary lesion using Olea Sphere software. Patients were stratified into three groups according to RP Gleason score (GS): ≤6, 7(3 + 4) and ≥7(4 + 3).

RESULTS

The mean rank of VEGF and TNFα was significantly different between the groups [H(2) = 11.038, P = 0.004] and [H(2) = 13.086, P = 0.001], respectively. Patients with stage pT₃ had higher TNFα (18.2 ± 8.95) positivity than patients with stage pT₂ (13.27 ± 10.66; t [67] = -2.03, P = 0.047). TNFα expression significantly correlated with K_trans (ρ = 0.327, P = 0.023). TNFα (P = 0.043), and VEGF (P = 0.02) correlated with high grade PCa (GS ≥ 7) in RP specimens and also correlated significantly with upgrading of GS from biopsy to RP histology.

CONCLUSIONS

The expression levels of TNFα and VEGF on immunostaining significantly correlated with aggressivity of PCa. As biomarkers, these indicate the risk of having high grade PCa in men undergoing RP.

Peri-prostatic Fat Volume Measurement as a Predictive Tool for Castration Resistance in Advanced Prostate Cancer

BACKGROUND

Obesity and aggressive prostate cancer (PC) may be linked, but how local peri-prostatic fat relates to tumour response following androgen deprivation therapy (ADT) is unknown.

OBJECTIVE

To test if peri-prostatic fat volume (PPFV) predicts tumour response to ADT.

DESIGN, SETTING, AND PARTICIPANTS

We performed a retrospective study on consecutive patients receiving primary ADT. From staging pelvic magnetic resonance imaging scans, the PPFV was quantified with OsirixX 6.5 imaging software. Statistical (univariate and multivariate) analysis were performed using R Version 3.2.1.

RESULTS AND LIMITATIONS

Of 224 consecutive patients, 61 with advanced (≥T3 or N1 or M1) disease had (3-mm high resolution axial sections) pelvic magnetic resonance imaging scan before ADT. Median age=75 yr; median PPFV=24.8cm3 (range, 7.4-139.4cm3). PPFV was significantly higher in patients who developed castration resistant prostate cancer (CRPC; n=31), with a median of 37.9cm3 compared with 16.1cm3 (p <0.0001, Wilcoxon rank sum test) in patients who showed sustained response to ADT (n=30). Multivariate analysis using Cox proportional hazards models were performed controlling for known predictors of CRPC. PPFV was shown to be independent of all included factors, and the most significant predictor of time to CRPC. Using our multivariate model consisting of all known factors prior to ADT, PPFV significantly improved the area under the curve of the multivariate models receiver operating characteristic analysis. The main study limitation is a relatively small cohort to account for multiple variables, necessitating a future large-scale prospective analysis of PPFV in advanced PC.

CONCLUSIONS

PPFV quantification in patients with advanced PC predicts tumour response to ADT.

PATIENT SUMMARY

The amount of fat around the prostate predicts prostate cancer response to hormone treatment.

The combination of prostate imaging reporting and data system version 2 (PI-RADS v2) and periprostatic fat thickness on multi-parametric MRI to predict the presence of prostate cancer

PURPOSE

To evaluate the auxiliary effectiveness of periprostatic fat thickness (PPFT) on multi-parametric magnetic resonance imaging (mp-MRI) to Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) in predicting the presence of prostate cancer (PCa) and high-grade prostate cancer (HGPCa, Gleason Score ≥ 7).

RESULTS

Overall, there were 371 patients (54.3%) with PCa and 292 patients (42.8%) with HGPCa. The mean value of PPFT was 4.04 mm. Multivariate analysis revealed that age, prostatic specific antigen (PSA), volume, PI-RADS score, and PPFT were independent predictors of PCa. All factors plus abnormal digital rectal exam were independent predictors of HGPCa. In addition, the PPFT was the independent predictor of PCa (Odds ratio [OR] 2.56, p = 0.004) and HGPCa (OR 2.70, p = 0.014) for subjects with PI-RADS grade 3. The present two nomograms based on multivariate analysis outperformed the single PI-RADS in aspects of predicting accuracy for PCa (area under the curve: 0.922 vs. 0.883, p = 0.029) and HGPCa (0.919 vs. 0.873, p = 0.007). Decision-curve analysis also indicated the favorable clinical utility of the present two nomograms.

MATERIALS AND METHODS

The clinical data of 683 patients who received transrectal ultrasound guided biopsy and prior mp-MRI were reviewed. PPFT was measured as the shortest perpendicular distance from the pubic symphysis to the prostate on MRI. Univariate and multivariate analyses were performed to determine the independent predictors of PCa and HGPCa. We also constructed two nomograms for predicting PCa and HGPCa based on the logistic regression.

CONCLUSION

The PPFT on mp-MRI is an independent predictor of PCa and HGPCa, notably for patients with PI-RADS grade 3. The nomograms incorporated predictors of PPFT and PI-RADS demonstrated good predictive performance.

Obesity does not promote tumorigenesis of localized patient-derived prostate cancer xenografts

There are established epidemiological links between obesity and the severity of prostate cancer. We directly tested this relationship by assessing tumorigenicity of patient-derived xenografts (PDXs) of moderate-grade localized prostate cancer in lean and obese severe combined immunodeficiency (SCID) mice. Mice were rendered obese and insulin resistant by high-fat feeding for 6 weeks prior to transplantation, and PDXs were assessed 10 weeks thereafter. Histological analysis of PDX grafts showed no differences in tumor pathology, prostate-specific antigen, androgen receptor and homeobox protein Nkx-3.1 expression, or proliferation index in lean versus obese mice. Whilst systemic obesity per se did not promote prostate tumorigenicity, we next asked whether the peri-prostatic adipose tissue (PPAT), which covers the prostate anteriorly, plays a role in prostate tumorigenesis. In vitro studies in a cellularized co-culture model of stromal and epithelial cells demonstrated that factors secreted from human PPAT are pro-tumorigenic. Accordingly, we recapitulated the prostate-PPAT spatial relationship by co-grafting human PPAT with prostate cancer in PDX grafts. PDX tissues were harvested 10 weeks after grafting, and histological analysis revealed no evidence of enhanced tumorigenesis with PPAT compared to prostate cancer grafts alone. Altogether, these data demonstrate that prostate cancer tumorigenicity is not accelerated in the setting of diet-induced obesity or in the presence of human PPAT, prompting the need for further work to define the at-risk populations of obesity-driven tumorigenesis and the biological factors linking obesity, adipose tissue and prostate cancer pathogenesis.

PI-RADS v2 and periprostatic fat measured on multiparametric magnetic resonance imaging can predict upgrading in radical prostatectomy pathology amongst patients with biopsy Gleason score 3 + 3 prostate cancer

PURPOSE

An underestimated biopsy Gleason score 3 + 3 can result in unfounded optimism amongst patients and cause physicians to miss the window for prostate cancer (PCa) cure. This study aims to evaluate the effectiveness of Prostate Imaging Reporting and Data System (PI-RADS) version 2 as well as periprostatic fat (PPF) measured on multiparametric magnetic resonance imaging (mp-MRI) at predicting pathological upgrading amongst patients with biopsy Gleason score 3 + 3 disease.

PATIENTS AND METHODS

A retrospective analysis of 56 patients with biopsy Gleason score 6 PCa who underwent prebiopsy mp-MRI and radical prostatectomy (RP) between November 2013 and March 2018 was conducted. Two radiologists performed PI-RADS v2 score evaluation and different fat measurements on mp-MRI. The associations amongst clinical information, PI-RADS v2 score, different fat parameters and pathologic findings were analyzed. A nomogram predicting upgrading was established based on the results of logistic regression analysis.

RESULTS

A total of 38 (67.9%) patients were upgraded to Gleason ≥7 disease on RP specimens. Prostate-specific antigen density (PSAD) (p < .001), positive core (p < .001), single-core positivity (p = .039), PI-RADS score (p < .001), front PPF area (p = .007) and front-to-total ratio (the ratio of front PPF area to total contour area) (p < .001) were risk factors for upgrading. On multivariate analysis, Epstein criteria (p = .02), PI-RADS score >3 (p = .024), and front-to-total ratio (p = .006) were independent risk factors for pathologic upgrading. The AUC value of the nomogram was 0.893 (95% CI, 0.787-0.999).

CONCLUSION

The combination of PI-RADS v2 and periprostatic fat measured on mp-MRI can help predict pathologic upgrading amongst patients with biopsy Gleason score 3 + 3 PCa.

Contribution of Adipose Tissue to Development of Cancer

Solid tumor growth and metastasis require the interaction of tumor cells with the surrounding tissue, leading to a view of tumors as tissue-level phenomena rather than exclusively cell-intrinsic anomalies. Due to the ubiquitous nature of adipose tissue, many types of solid tumors grow in proximate or direct contact with adipocytes and adipose-associated stromal and vascular components, such as fibroblasts and other connective tissue cells, stem and progenitor cells, endothelial cells, innate and adaptive immune cells, and extracellular signaling and matrix components. Excess adiposity in obesity both increases risk of cancer development and negatively influences prognosis in several cancer types, in part due to interaction with adipose tissue cell populations. Herein, we review the cellular and noncellular constituents of the adipose "organ," and discuss the mechanisms by which these varied microenvironmental components contribute to tumor development, with special emphasis on obesity. Due to the prevalence of breast and prostate cancers in the United States, their close anatomical proximity to adipose tissue depots, and their complex epidemiologic associations with obesity, we particularly highlight research addressing the contribution of adipose tissue to the initiation and progression of these cancer types. Obesity dramatically modifies the adipose tissue microenvironment in numerous ways, including induction of fibrosis and angiogenesis, increased stem cell abundance, and expansion of proinflammatory immune cells. As many of these changes also resemble shifts observed within the tumor microenvironment, proximity to adipose tissue may present a hospitable environment to developing tumors, providing a critical link between adiposity and tumorigenesis. © 2018 American Physiological Society. Compr Physiol 8:237-282, 2018.

Phase II prospective randomized trial of weight loss prior to radical prostatectomy

BACKGROUND

Obesity is associated with poorly differentiated and advanced prostate cancer and increased mortality. In preclinical models, caloric restriction delays prostate cancer progression and prolongs survival. We sought to determine if weight loss (WL) in men with prostate cancer prior to radical prostatectomy affects tumor apoptosis and proliferation, and if WL effects other metabolic biomarkers.

METHODS

In this Phase II prospective trial, overweight and obese men scheduled for radical prostatectomy were randomized to a 5–8 week WL program consisting of standard structured energy-restricted meal plans (1200–1500 Kcal/day) and physical activity or to a control group. The primary endpoint was apoptotic index in the radical prostatectomy malignant epithelium. Secondary endpoints were proliferation (Ki67) in the radical prostatectomy tissue, body weight, body mass index (BMI), waist to hip ratio, body composition, and serum PSA, insulin, triglyceride, cholesterol, testosterone, estradiol, leptin, adiponectin, interleukin 6, interleukin 8, insulin-like growth factor 1, and IGF binding protein 1.

RESULTS

Twenty-three patients were randomized to the WL intervention and twenty-one patients to the control group. Subjects in the intervention group had significantly more weight loss (WL:−3.7 ± 0.5 kg; Control:−1.6 ± 0.5 kg; p=0.007) than the control group and total fat mass was significantly reduced (WL:−2.1 ± 0.4; Control: 0.1 ± 0.3; p=0.015). There was no significant difference in apoptotic or proliferation index between the groups. Among the other biomarkers, triglyceride and insulin levels were significantly decreased in the WL compared to the control group.

CONCLUSIONS

In summary, this short-term WL program prior to radical prostatectomy resulted in significantly more WL in the intervention vs. the control group and was accompanied by significant reductions in body fat mass, circulating triglycerides, and insulin. However, no significant changes were observed in malignant epithelium apoptosis or proliferation. Future studies should consider a longer term or more intensive weight loss intervention.

Normalized periprostatic fat MRI measurements can predict prostate cancer aggressiveness in men undergoing radical prostatectomy for clinically localised disease

Periprostatic and pelvic fat have been shown to influence prostate cancer behaviour through the secretion of chemokines and growth factors, acting in a paracrine mode. We have measured periprostatic fat volume (PFV) with normalisation to prostate gland volume on pelvic magnetic resonance imaging (MRI) and have correlated this with grade (Gleason score; GS) and pathological staging (pT) of prostate cancer (PCa) following radical prostatectomy (RP). PFV was determined using a segmentation technique on contiguous T1-weighted axial MRI slices from the level of the prostate base to the apex. The abdominal fat area (AFA) and subcutaneous fat thickness (SFT) were measured using T1-weighted axial slices at the level of the umbilicus and the upper border of the symphysis pubis, respectively. PFV was normalised to prostate volume (PV) to account for variations in PV (NPFV = PFV/PV). Patients were stratified into three risk groups according to post-operative GS: ≤6, 7(3 + 4), and ≥7(4 + 3). NPFV was significantly different between the groups (p = 0.001) and positively correlated with post-operative GS (ρ = 0.294, p < 0.001). There was a difference in NPFV between those with upgrading of GS from 6 post prostatectomy (2.43 ± 0.98; n = 26) compared to those who continued to be low grade (1.99 ± 0.82; n = 17); however, this did not reach statistical significance (p = 0.11).

Periprostatic adipose inflammation is associated with high-grade prostate cancer

Background

Obesity, a cause of subclinical inflammation, is associated with increased risk of high grade prostate cancer (PC) and poor outcomes. Whether inflammation occurs in periprostatic white adipose tissue (WAT), and contributes to the negative impact of obesity on PC aggressiveness, is unknown.

Methods

In a single-center, cross-sectional design, men with newly diagnosed PC undergoing radical prostatectomy were eligible for study participation. The primary objective was to examine the prevalence of periprostatic WAT inflammation defined by the presence of crown-like structures (CLS-P) as detected by CD68 immunohistochemistry. Secondary objectives were to explore the clinical and systemic correlates of periprostatic WAT inflammation. Tumor characteristics and host factors including BMI, adipocyte diameter, and circulating levels of lipids, adipokines, and other metabolic factors were measured. Wilcoxon rank-sum, Chi-square, or Fisher’s exact tests, and generalized linear regression were used to examine the association between WAT inflammation and tumor and host characteristics.

Results

Periprostatic fat was collected from 169 men (median age 62 years; median BMI 28.3). Periprostatic WAT inflammation was identified in 49.7% of patients and associated with higher BMI (P=0.02), larger adipocyte size (P=0.004), and Gleason grade groups IV/V tumors (P=0.02). The relationship between WAT inflammation and high Gleason grade remained significant after adjusting for BMI (P=0.04). WAT inflammation correlated with higher circulating levels of insulin, triglycerides, and leptin/adiponectin ratio, and lower high density lipoprotein cholesterol, compared to those without WAT inflammation (P’s <0.05).

Conclusions

Periprostatic WAT inflammation is common in this cohort of men with PC and is associated with high grade PC.

Role of MRI in the Risk Assessment of Primary Prostate Cancer

A successful paradigm shift toward personalized management strategies for patients with prostate cancer (PCa) is heavily dependent on the availability of noninvasive diagnostic tools capable of accurately establishing the true extent of disease at the time of diagnosis and estimating the risk of subsequent disease progression and related mortality. Although there is still considerable scope for improvement in its diagnostic, predictive, and prognostic capabilities, multiparametric prostate magnetic resonance imaging (MRI) is currently regarded as the imaging modality of choice for local staging of PCa. A negative MRI, that is, the absence of any MRI-visible intraprostatic lesion, has a high negative predictive value for the presence of clinically significant PCa and can substantiate the consideration of active surveillance as a preferred initial management approach. MRI-derived quantitative and semi-quantitative parameters can be utilized to noninvasively characterize MRI-visible prostate lesions and identify those patients who are most likely to benefit from radical treatment, and differentiate them from patients with benign or indolent prostate pathology that may also be visible on MRI. This literature review summarizes current strategies how MRI can be used to determine a tailored management strategy for an individual patient.

Prostate cancer-specific mortality after radical prostatectomy: value of preoperative MRI

BACKGROUND

Although magnetic resonance imaging (MRI) is currently indispensable in the preoperative setting of biopsy-proven prostate cancer, the value of preoperative MRI for predicting prostate cancer-specific mortality (PCSM) is not well known.

PURPOSE

To evaluate the value of MRI for predicting PCSM in patients who underwent radical prostatectomy (RP) for localized prostate cancer.

MATERIAL AND METHODS

A total of 318 patients underwent MRI followed by RP. MRI was assessed for the presence of clinically significant cancer using a five-point Likert scale, where ≥4 was considered positive. Cox proportional hazards regression analyses was used to determine the relationship of preoperative factors with PCSM. PCSM was calculated using the Kaplan-Meier method and compared between factors using the log-rank test.

RESULTS

After a median follow-up of 104 months, 11 (3.5%) patients died of prostate cancer. One hundred and four (32.7%) patients had clinically significant prostate cancer on MRI. Univariate analysis revealed that Gleason grade, greatest percentage of involved core length (GPCL), and clinically significant cancer on MRI were significantly related to PCSM (P = 0.001-0.003). Multivariate analysis showed that GPCL (hazard ratio [HR], 1.028; 95% confidence interval [CI], 1.000-1.057; P = 0.048) and clinically significant cancer on MRI (HR, 10.903; 95% CI, 1.287-92.374; P = 0.028) were independent predictors of PCSM. The 5 - and 10-year PCSM rates were 0.6% and 1.3% in patients with GPCL <50% and 5.1% and 8.6% in those with GPCL ≥50% (P = 0.012). Patients without clinically significant cancer on MRI showed 5 - and 10-year PCSM rates of 0% and 0.5%, respectively, whereas those with clinically significant cancer on MRI showed rates of 8% and 14.2%, respectively (P < 0.001).

CONCLUSION

Preoperative MRI and GPCL may be used to predict PCSM after RP.

PI-RADS version 2 for prediction of pathological downgrading after radical prostatectomy: a preliminary study in patients with biopsy-proven Gleason Score 7 (3+4) prostate cancer

OBJECTIVES

To evaluate PI-RADSv2 for predicting pathological downgrading after radical prostatectomy (RP) in patients with biopsy-proven Gleason score (GS) 7(3+4) PC.

METHODS

A total of 105 patients with biopsy-proven GS 7(3+4) PC who underwent multiparametric prostate MRI followed by RP were included. Two radiologists assigned PI-RADSv2 scores for each patient. Preoperative clinicopathological variables and PI-RADSv2 scores were compared between patients with and without downgrading after RP using the Wilcoxon rank sum test or Fisher's exact test. Logistic regression analyses with Firth's bias correction were performed to assess their association with downgrading.

RESULTS

Pathological downgrading was identified in ten (9.5 %) patients. Prostate-specific antigen (PSA), PSA density, percentage of cores with GS 7(3+4), and greatest percentage of core length (GPCL) with GS 7(3+4) were significantly lower in patients with downgrading (p = 0.002-0.037). There was no significant difference in age and clinical stage (p = 0.537-0.755). PI-RADSv2 scores were significantly lower in patients with downgrading (3.8 versus 4.4, p = 0.012). At univariate logistic regression analysis, PSA, PSA density, and PI-RADSv2 scores were significant predictors of downgrading (p = 0.003-0.022). Multivariate analysis revealed only PSA density and PI-RADSv2 scores as independent predictors of downgrading (p = 0.014-0.042).

CONCLUSIONS

The PI-RADSv2 scoring system was an independent predictor of pathological downgrading after RP in patients with biopsy-proven GS 7(3+4) PC.

KEY POINTS

• PI-RADSv2 was an independent predictor of downgrading in biopsy-proven GS 7(3+4) PC • PSA density was also an independent predictor of downgrading • MRI may assist in identifying AS candidates in biopsy-proven GS 7(3+4) PC patients.

Linking obesogenic dysregulation to prostate cancer progression

The global epidemic of obesity is closely linked to the development of serious co-morbidities, including many forms of cancer. Epidemiological evidence consistently shows that obesity is associated with a similar or mildly increased incidence of prostate cancer but, more prominently, an increased risk for aggressive prostate cancer and prostate cancer-specific mortality. Studies in mice demonstrate that obesity induced by high-fat feeding increases prostate cancer progression; however, the mechanisms underpinning this relationship remain incompletely understood. Adipose tissue expansion in obesity leads to local tissue dysfunction and is associated with low-grade inflammation, alterations in endocrine function and changes in lipolysis that result in increased delivery of fatty acids to tissues of the body. The human prostate gland is covered anteriorly by the prominent peri-prostatic adipose tissue and laterally by smaller adipose tissue depots that lie directly adjacent to the prostatic surface. We discuss how the close association between dysfunctional adipose tissue and prostate epithelial cells might result in bi-directional communication to cause increased prostate cancer aggressiveness and progression. However, the literature indicates that several 'mainstream' hypotheses regarding obesity-related drivers of prostate cancer progression are not yet supported by a solid evidence base and, in particular, are not supported by experiments using human tissue. Understanding the links between obesity and prostate cancer will have major implications for the health policy for men with prostate cancer and the development of new therapeutic or preventative strategies.