Uncovering prostate cancer aggressiveness signal in T2-weighted MRI through a three-reference tissues normalization technique.

Quantitative T2-weighted MRI (T2W) interpretation is impeded by the variability of acquisition-related features, such as field strength, coil type, signal amplification, and pulse sequence parameters. The main purpose of this work is to develop an automated method for prostate T2W intensity normalization. The procedure includes the following: (i) a deep learning-based network utilizing MASK R-CNN for automatic segmentation of three reference tissues: gluteus maximus muscle, femur, and bladder; (ii) fitting a spline function between average intensities in these structures and reference values; and (iii) using the function to transform all T2W intensities. The T2W distributions in the prostate cancer regions of interest (ROIs) and normal appearing prostate tissue (NAT) were compared before and after normalization using Student's t-test. The ROIs' T2W associations with the Gleason Score (GS), Decipher genomic score, and a three-tier prostate cancer risk were evaluated with Spearman's correlation coefficient (rS ). T2W differences in indolent and aggressive prostate cancer lesions were also assessed. The MASK R-CNN was trained with manual contours from 32 patients. The normalization procedure was applied to an independent MRI dataset from 83 patients. T2W differences between ROIs and NAT significantly increased after normalization. T2W intensities in 231 biopsy ROIs were significantly negatively correlated with GS (rS = -0.21, p = 0.001), Decipher (rS = -0.193, p = 0.003), and three-tier risk (rS = -0.235, p < 0.001). The average T2W intensities in the aggressive ROIs were significantly lower than in the indolent ROIs after normalization. In conclusion, the automated triple-reference tissue normalization method significantly improved the discrimination between prostate cancer and normal prostate tissue. In addition, the normalized T2W intensities of cancer exhibited a significant association with tumor aggressiveness. By improving the quantitative utilization of the T2W in the assessment of prostate cancer on MRI, the new normalization method represents an important advance over clinical protocols that do not include sequences for the measurement of T2 relaxation times.

Clinical-Genomic Risk Group Classification of Suspicious Lesions on Prostate Multiparametric-MRI.

The utilization of multi-parametric MRI (mpMRI) in clinical decisions regarding prostate cancer patients' management has recently increased. After biopsy, clinicians can assess risk using National Comprehensive Cancer Network (NCCN) risk stratification schema and commercially available genomic classifiers, such as Decipher. We built radiomics-based models to predict lesions/patients at low risk prior to biopsy based on an established three-tier clinical-genomic classification system. Radiomic features were extracted from regions of positive biopsies and Normally Appearing Tissues (NAT) on T2-weighted and Diffusion-weighted Imaging. Using only clinical information available prior to biopsy, five models for predicting low-risk lesions/patients were evaluated, based on: 1: Clinical variables; 2: Lesion-based radiomic features; 3: Lesion and NAT radiomics; 4: Clinical and lesion-based radiomics; and 5: Clinical, lesion and NAT radiomic features. Eighty-three mpMRI exams from 78 men were analyzed. Models 1 and 2 performed similarly (Area under the receiver operating characteristic curve were 0.835 and 0.838, respectively), but radiomics significantly improved the lesion-based performance of the model in a subset analysis of patients with a negative Digital Rectal Exam (DRE). Adding normal tissue radiomics significantly improved the performance in all cases. Similar patterns were observed on patient-level models. To the best of our knowledge, this is the first study to demonstrate that machine learning radiomics-based models can predict patients' risk using combined clinical-genomic classification.

Experimental Support for the Possibility of Retrograde Genesis of Intraductal Carcinoma of the Prostate.

Background. Historically, intraductal carcinoma of the prostate (IDC-P) was postulated to be a retrograde spread of high-grade invasive prostate cancer. There is evidence that IDC-P can primarily originate in the prostatic ducts. The retrograde genesis has never been experimentally or clinically confirmed before. Methods. Biopsy proven intermediate or high-risk prostate cancer was orthotopically grafted in the prostate of severe combined immunodeficiency gamma mice. Cancer growth was monitored by serum PSA levels. The animals were sacrificed and grafted areas were histological examined. Results. Twenty-one of 23 mice survived and demonstrated rising serum PSA. In 10 of 21 animals, human prostate cancer was identified orthotopically. Except for one case where the human biopsy showed a Grade Group 2 prostate cancer and mouse graft was Grade Group 5, other 9 specimens showed comparable grades. One of the specimens demonstrated a cribriform invasive prostate cancer and adjacent IDC-P. Conclusion. These experimental data offer some evidence that invasive prostate cancer can demonstrate a retrograde spread in the prostatic ducts as IDC-P. Its ability to primarily arise in the ducts has been demonstrated in other studies. However, the issue which remains unresolved is in its most common presentation of IDC-P intermixed with high-grade invasive cancer if it is the former or the latter which came first. Possibly resolving this dilemma will shed some light on the existing controversies if IDC-P should or should not be graded when invasive cancer is present.

Longitudinal Changes and Predictive Value of Multiparametric MRI Features for Prostate Cancer Patients Treated with MRI-Guided Lattice Extreme Ablative Dose (LEAD) Boost Radiotherapy.

We investigated the longitudinal changes in multiparametric MRI (mpMRI) (T2-weighted, Apparent Diffusion Coefficient (ADC), and Dynamic Contrast Enhanced (DCE-)MRI) of prostate cancer patients receiving Lattice Extreme Ablative Dose (LEAD) radiotherapy (RT) and the capability of their imaging features to predict RT outcome based on endpoint biopsies. Ninety-five mpMRI exams from 25 patients, acquired pre-RT and at 3-, 9-, and 24-months post-RT were analyzed. MRI/Ultrasound-fused biopsies were acquired pre- and at two-years post-RT (endpoint). Five regions of interest (ROIs) were analyzed: Gross tumor volume (GTV), normally-appearing tissue (NAT) and peritumoral volume in both peripheral (PZ) and transition (TZ) zones. Diffusion and perfusion radiomics features were extracted from mpMRI and compared before and after RT using two-tailed Student t-tests. Selected features at the four scan points and their differences (Δ radiomics) were used in multivariate logistic regression models to predict the endpoint biopsy positivity. Baseline ADC values were significantly different between GTV, NAT-PZ, and NAT-TZ (p-values < 0.005). Pharmaco-kinetic features changed significantly in the GTV at 3-month post-RT compared to baseline. Several radiomics features at baseline and three-months post-RT were significantly associated with endpoint biopsy positivity and were used to build models with high predictive power of this endpoint (AUC = 0.98 and 0.89, respectively). Our study characterized the RT-induced changes in perfusion and diffusion. Quantitative imaging features from mpMRI show promise as being predictive of endpoint biopsy positivity.

Heterogeneity in Genomic Risk Assessment from Tissue Based Prognostic Signatures Used in the Biopsy Setting and the Impact of Magnetic Resonance Imaging Targeted Biopsy.

PURPOSE: Genomic prognostic signatures are used on prostate biopsy tissue for cancer risk assessment, but tumor heterogeneity and multifocality may be an issue. We evaluated the variability in genomic risk assessment from different biopsy cores within the prostate using 3 prognostic signatures (Decipher, CCP, GPS). MATERIALS AND METHODS: Men in this study came from 2 prospective prostate cancer trials of patients undergoing multiparametric magnetic resonance imaging and magnetic resonance imaging targeted biopsy with genomic profiling of positive biopsy cores. We explored the relationship among tumor grade, magnetic resonance imaging risk and genomic risk for each signature. We evaluated the variability in genomic risk assessment between different biopsy cores and assessed how often magnetic resonance imaging targeted biopsy or the current standard of care (profiling the core with the highest grade) resulted in the highest genomic risk level. RESULTS: In all, 224 positive biopsy cores from 78 men with prostate cancer were profiled. For each signature, higher biopsy grade (p <0.001) and magnetic resonance imaging risk level (p <0.001) were associated with higher genomic scores. Genomic scores from different biopsy cores varied with risk categories changing by 21% to 62% depending on which core or signature was used. Magnetic resonance imaging targeted biopsy and profiling the core with the highest grade resulted in the highest genomic risk level in 72% to 84% and 75% to 87% of cases, respectively, depending on the signature used. CONCLUSIONS: There is variation in genomic risk assessment from different biopsy cores regardless of the signature used. Magnetic resonance imaging directed biopsy or profiling the highest grade core resulted in the highest genomic risk level in most cases.

Self-Identified African Americans and prostate cancer risk: West African genetic ancestry is associated with prostate cancer diagnosis and with higher Gleason sum on biopsy.

Concerns about overtreatment of clinically indolent prostate cancer (PrCa) have led to recommendations that men who are diagnosed with low-risk PrCa be managed by active surveillance (AS) rather than immediate definitive treatment. However the risk of underestimating the aggressiveness of a patient's PrCa can be a significant source of anxiety and a barrier to patient acceptance of AS. The uncertainty is particularly keen for African American (AA) men who are about 1.7 times more likely to be diagnosed with PrCa than European American (EA) men and about 2.4 times more likely to die of this disease. The AA population, as many other populations in the Americas, is genetically heterogeneous with varying degrees of admixture from West Africans (WAs), Europeans, and Native Americans (NAs). Recommendations for PrCa screening and management rarely consider potential differences in risk within the AA population. We compared WA genetic ancestry in AA men undergoing standard prostate biopsy who were diagnosed with no cancer, low-grade PrCa (Gleason Sum 6), or higher grade PrCa (Gleason Sum 7-10). We found that WA genetic ancestry was significantly higher in men who were diagnosed with PrCa on biopsy, compared to men who were cancer-negative, and highest in men who were diagnosed with higher grade PrCa (Gleason Sum 7-10). Incorporating WA ancestry into the guidelines for making decisions about when to obtain a biopsy and whether to choose AS may allow AA men to personalize their approach to PrCa screening and management.

Nitrocellulose tissue prints: an innovative approach to preparing high quality DNA and RNA from prostate biopsies without compromising the cores for pathology diagnosis.

Much of the research that has been done on prostate cancer tissue biomarkers has relied on radical prostatectomies for biospecimens. However, it is well recognized that important groups of patients are under-represented or missing entirely from biorepository collections of radical prostatectomy specimens. Using prostate biopsy tissues for molecular biomarker research significantly expands the range of available patients to include men whose biopsies show no cancer as well as men who are treated non-surgically or who choose active surveillance. However, one of the challenges of biopsy-based biomarker research is the limited amount of tissue that can be obtained from each core. To address this challenge, we have developed and fully implemented innovative biopsy tissue print technologies that allow us to obtain high quality RNA and DNA from each biopsy core without compromising the specimen for a pathologic diagnosis. Prostate biopsy tissue print samples have been successfully utilized for gene expression profiling, genotyping, DNA methylation and sequencing analyses. Emerging biopsy tissue print applications include studies using viable cells to study tumor metabolism and drug response.

Epigenetic risk score improves prostate cancer risk assessment.

BACKGROUND: Early detection of aggressive prostate cancer (PCa) remains crucial for effective treatment of patients. However, PCa screening remains controversial due to a high rate of overdiagnosis and overtreatment. To better reconcile both objectives, more effective methods for assessing disease severity at the time of diagnosis are needed. METHODS: The relationship between DNA-methylation and high-grade PCa was examined in a cohort of 102 prospectively enrolled men who received standard 12-core prostate biopsies. EpiScore, an algorithm that quantifies the relative DNA methylation intensities of GSTP1, RASSF1, and APC in prostate biopsy tissue, was evaluated as a method to compensate for biopsy under-sampling and improve risk stratification at the time of diagnosis. RESULTS: DNA-methylation intensities of GSTP1, RASSF1, and APC were higher in biopsy cores from men diagnosed with GS ≥ 7 cancer compared to men with diagnosed GS 6 disease. This was confirmed by EpiScore, which was significantly higher for subjects with high-grade biopsies and higher NCCN risk categories (both P < 0.001). In patients diagnosed with GS ≥ 7, increased levels of DNA-methylation were present, not only in the high-grade biopsy cores, but also in other cores with no or low-grade disease (P < 0.001). By combining EpiScore with traditional clinical risk factors into a logistic regression model, the prediction of high GS reached an AUC of 0.82 (95%CI: 0.73-0.91) with EpiScore, DRE, and atypical histological findings as most important contributors. CONCLUSIONS: In men diagnosed with PCa, DNA-methylation profiling can detect under-sampled high-risk PCa in prostate biopsy specimens through a field effect. Predictive accuracy increased when EpiScore was combined with other clinical risk factors. These results suggest that EpiScore could aid in the detection of occult high-grade disease at the time of diagnosis, thereby improving the selection of candidates for Active Surveillance.

An illustration of the potential for mapping MRI/MRS parameters with genetic over-expression profiles in human prostate cancer.

INTRODUCTION: Magnetic resonance imaging (MRI) and MR spectroscopy can probe a variety of physiological (e.g. blood vessel permeability) and metabolic characteristics of prostate cancer. However, little is known about the changes in gene expression that underlie the spectral and imaging features observed in prostate cancer. Tumor induced changes in vascular permeability and angiogenesis are thought to contribute to patterns of dynamic contrast enhanced (DCE) MRI images of prostate cancer even though the genetic basis of tumor vasculogenesis is complex and the specific mechanisms underlying these DCEMRI features have not yet been determined. MATERIALS AND METHODS: In order to identify the changes in gene expression that correspond to MRS and DCEMRI patterns in human prostate cancers, we have utilized tissue print micropeel techniques to generate "whole mount" molecular maps of radical prostatectomy specimens that correspond to pre-surgical MRI/MRS studies. These molecular maps include RNA expression profiles from both Affymetrix GeneChip microarrays and quantitative reverse transcriptase PCR (qrt-PCR) analysis, as well as immunohistochemical studies. RESULTS: Using these methods on patients with prostate cancer, we found robust over-expression of choline kinase a in the majority of primary tumors. We also observed overexpression of neuropeptide Y (NPY), a newly identified angiogenic factor, in a subset of prostate cancers, visualized on DCEMRI. CONCLUSION: These studies set the stage for establishing MRI/MRS parameters as validated biomarkers for human prostate cancer.

DNA degradation test predicts success in whole-genome amplification from diverse clinical samples.

The need to apply modern technologies to analyze DNA from diverse clinical samples often stumbles on suboptimal sample quality. We developed a simple approach to assess DNA fragmentation in minute clinical samples of widely different origin and the likelihood of success of degradation-tolerant whole genome amplification (restriction and circularization-aided rolling circle amplification, RCA-RCA) and subsequent polymerase chain reaction (PCR). A multiplex PCR amplification of four glyceraldehyde-3-phosphate dehydrogenase amplicons of varying sizes was performed using genomic DNA from clinical samples, followed by size discrimination on agarose gel or fluorescent denaturing high-performance liquid chromatography (dHPLC). RCA-RCA followed by real-time PCR was also performed, for correlation. Even minimal quantities of longer PCR fragments ( approximately 300 to 400 bp), visible via high-sensitivity fluorescent dHPLC or agarose gel, were essential for the success of RCA-RCA and subsequent PCR-based assays. dHPLC gave a more accurate correlation between DNA fragmentation and sample quality than agarose gel electrophoresis. Multiplex-PCR-dHPLC predicted correctly the likelihood of assay success in formalin-fixed, paraffin-embedded samples fixed under controlled conditions and of different ages, in laser capture microdissection samples, in tissue print micropeels, and plasma-circulating DNA. Estimates of the percent information retained relative to snap-frozen DNA are derived for real-time PCR analysis. The assay is rapid and convenient and can be used widely to characterize DNA from any clinical sample of unknown quality.

Tissue print micropeel: a new technique for mapping tumor invasion in prostate cancer.

Because of widely adopted screening programs for early detection of prostate cancers, many patients who undergo radical prostatectomy have tumors that are not grossly evident, and the extent and distribution of the cancer in the gland can only be determined by a microscopic examination of the surgical specimen. Historically, one of the most important predictors of the quality of cancer control following surgical resection of a solid tumor is the absence of cancer at the surgical margins. Although the clinical significance of cancer at the margins of a radical prostatectomy specimen has been a source of controversy in recent years, surgical pathology assessment of radical prostatectomy margins remains an important part of prostate cancer clinical care. However, a comprehensive histopathologic review of every radical prostatectomy specimen is beyond the resources of most hospitals. Tissue print micropeel technologies, combined with appropriate markers, provide a new strategy that combines a relatively simple technique for sampling specimen margins with a method for obtaining molecular information about the cancer that can add to the macroscopic and microscopic anatomical findings. This new tissue printing approach for incorporating molecular markers into the assessment of radical prostatectomy margins is reviewed in this article.

Development of a sensitive and specific enzyme-linked immunosorbent assay for thymosin beta15, a urinary biomarker of human prostate cancer.

OBJECTIVES: In tissue-based assays, thymosin beta15 (Tbeta15) has been shown to correlate with prostate cancer (CaP) malignancy and with future recurrence. To be clinically effective, it must be shown that Tbeta15 is released by the tumor into body fluids in detectable concentrations. Toward this end, we have worked to develop a quantitative high-throughput assay that can accurately measure clinically relevant concentrations of Tbeta15 in human urine. DESIGN AND METHODS: Sixteen antibodies were raised against recombinant Tbeta15 and/or peptide conjugates. One antibody, having stable characteristics over the wide range of pH and salt concentrations found in urine and minimal cross-reactivity with other beta thymosins, was used to develop a competitive enzyme-linked immunosorbent assay (ELISA). Urinary Tbeta15 concentration was determined for control groups; normal (N = 52), prostate intraepithelial neoplasia (PIN, N = 36), and CaP patients; untreated (N = 7) with subsequent biochemical failure, radiation therapy (N = 17) at risk of biochemical recurrence. RESULTS: The operating range of the competition ELISA fell between 2.5 and 625 ng/mL. Recoveries exceeded 75%, and the intra- and inter-assay coefficients of variability were 3.3% and 12.9%, respectively. No cross-reactivity with other urine proteins was observed. A stable Tbeta15 signal was recovered from urine specimens stored at -20 degrees C for up to 1 year. At a threshold of 40 (ng/dL)/mug protein/mg creatinine), the assay had a sensitivity of 58% and a specificity of 94%. Relative to the control groups, Tbeta15 levels were greater than this threshold in a significant fraction of the CaP patients (P < 0.001), including 5 of the 7 patients who later experienced PSA recurrence. CONCLUSIONS: We have established an ELISA that is able to detect Tbeta15 at clinically relevant concentrations in urine from patients with CaP. The assay will provide a tool for future clinical trials to validate urinary Tbeta15 as a predictive marker for recurrent CaP.

Use of thymosin beta15 as a urinary biomarker in human prostate cancer.

BACKGROUND: Additional prostate cancer (CaP) biomarkers are needed to increase the accuracy of diagnosis and to identify patients at risk of recurrence. In tissue-based assays, thymosin beta15 (Tbeta15) has been linked to an aggressive CaP phenotype and correlated with future tumor recurrence. We hypothesized that Tbeta15 may have clinical utility in biological fluids. METHODS: Tbeta15 was measured in urine from CaP patients; untreated (N = 61), prostatectomy (RP, N = 46), androgen deprivation therapy (ADT, N = 14) and control groups; normal (N = 52), genitourinary carcinoma (N = 15), non-malignant prostate disease (N = 81), and other urology (N = 73). We evaluated the utility of urinary Tbeta15 for CaP diagnosis, alone or in combination with prostate-specific antigen (PSA), and the relationship to CaP progression. RESULTS: A normal threshold of 40 (ng/dl)/(mug_protein/mg_creatinine) was defined using receiver operating characteristic analysis and marked the 19th centile for age-matched controls. The proportion of untreated CaP patients with urinary Tbeta15 above the threshold was significantly higher than normal and genitourinary disease controls (P < 0.001). RP caused urinary Tbeta15 to drop significantly (P = 0.005). Pre-surgery Tbeta15 concentrations greater than the normal threshold may confer greater risk of CaP recurrence. Relative to normal controls, patients receiving ADT for aggressive CaP were 12 times more likely to have elevated urinary Tbeta15 (P = 0.001, 95% CI = 2.8, 51.8). Combining PSA and Tbeta15 (PSA > 4, or PSA > 2.5, Tbeta15 > 40, or PSA = 2.5, Tbeta15 > 90) provided the same sensitivity as a 2.5 ng/ml PSA cutoff, but markedly improved diagnostic specificity. CONCLUSIONS: We report that Tbeta15 is a urinary biomarker for CaP and suggest that Tbeta15, in combination with PSA, can be used to improve both the sensitivity and specificity of CaP diagnosis.

Tissue-print and print-phoresis as platform technologies for the molecular analysis of human surgical specimens: mapping tumor invasion of the prostate capsule.

Molecular profiling of human biopsies and surgical specimens is frequently complicated by their inherent biological heterogeneity and by the need to conserve tissue for clinical diagnosis. We have developed a set of novel 'tissue print' and 'print-phoresis' technologies to facilitate tissue and tumor-marker profiling under these circumstances. Tissue printing transfers cells and extracellular matrix components from a tissue surface onto nitrocellulose membranes, generating a two-dimensional anatomical image on which molecular markers can be visualized by specific protein and RNA- and DNA-detection techniques. Print-phoresis is a complementary new electrophoresis method in which thin strips from the print are subjected to polyacrylamide gel electrophoresis, providing a straightforward interface between the tissue-print image and gel-based proteomic techniques. Here we have utilized these technologies to identify and characterize markers of tumor invasion of the prostate capsule, an event generally not apparent to the naked eye that may result in tumor at the surgical margins ('positive margins'). We have also shown that tissue-print technologies can provide a general platform for the generation of marker maps that can be superimposed directly onto histopathological and radiological images, permitting molecular identification and classification of individual malignant lesions.

The cell cycle and its relevance to the urologist.

PURPOSE: We surveyed fundamental concepts of the cell cycle to help the average urologist better understand the molecular basis for specific aspects of urological disease. MATERIALS AND METHODS: Important publications that have shaped our current understanding of the cell cycle were selected for review. Definitions of key terms are provided in a glossary. RESULTS: Cell proliferation, survival and programmed cell death (apoptosis) are the net result of a complex interaction of molecular signals that regulate DNA and protein synthesis. Many of the abnormal patterns of cell behavior that contribute to the pathology of malignant urological disease arise from disruptions in the molecular controls that normally regulate the cell cycle. Benign urological conditions, including cystic diseases and hypertrophy, also reflect abnormal growth that results from the disruption of cell cycle controls. CONCLUSIONS: This review is designed for the clinician and for the nonspecialist who is interested in the science of the cell cycle and its regulation as it broadly pertains to urological disease. Recent advances in the understanding of cell cycle regulation are presented with clinical correlations illustrating how these processes are involved in coordinating cell growth and cell death at the molecular level.

Determinations of prostate volume at 3-Tesla using an external phased array coil: comparison to pathologic specimens.

RATIONALE AND OBJECTIVES: To compare techniques for measuring in vivo prostate volumes using torso phased-array imaging at 3-Tesla. METHODS: Eleven patients imaged at 3-Tesla with a torso-phased array coil using multiplanar fast spin echo (FSE) T2-weighted imaging who underwent radical prostatectomy comprised the study population. Surgical specimens were imaged. The pathologic specimen volume was compared with varieties of magnetic resonance volume determinations, the latter using ellipsoid and planimetric assessments. Three-dimensional images of the excised prostate were generated. Linear correlation coefficients were calculated comparing volume determinations from image data and pathologic data. RESULTS: Correlation coefficient (r2) values from the ellipsoid formula among six different data sets ranging between 0.325 to 0.751; the highest in vivo r2 value was obtained by multiplying the anterior-posterior and the superior-inferior dimensions from the sagittal image by the right-left dimension from the axial image. The r2 values of the planimetric volume and specimen 3-dimensional volume rendering were 0.652 and 0.86, respectively. CONCLUSIONS: Surface coil prostate imaging at 3-Tesla provides undistorted images for volume assessment and in vivo volume determinations very close to ex vivo imaging volume determinations.

Inhibition of orthotopic growth and metastasis of androgen-sensitive human prostate tumors in mice by bioactive soybean components.

BACKGROUND: Systematic analysis of the influence of diet on the initiation and progression of prostate cancer is often difficult in human populations, for which dietary variables overlap a diversity of genetic backgrounds and social behaviors. Animal models that emulate human prostate cancer allow experimental analysis of the mechanisms of action of nutritional agents that show anti-prostate cancer activity. METHODS: We have used an orthotopic implant model to characterize the in vivo response of androgen-sensitive LNCaP prostate tumors to three well-characterized soy dietary supplements: isoflavone depleted soy protein, soy phytochemical concentrate (SPC), and genistin. RESULTS: In male SCID mice orthotopically implanted with the androgen-sensitive human prostate cell line LNCaP, dietary supplements of soy protein, genistin, and SPC reduced primary tumor weight by 42% (P = 0.07), 57% (P < 0.05) and 70% (P < 0.005), respectively. All three soy supplements significantly increased tumor apoptosis and decrease microvessel density, with no significant change in tumor proliferation. Each supplement produced a distinct serum androgen response, with genistin producing the greatest decrease in total serum testosterone and dihydrotestosterone (DHT) (P < 0.05) and the greatest increase in testosterone to DHT ratio (P < 0.05) and soy protein the greatest decrease in bioactive androgen (P < 0.05). Only SPC significantly inhibited metastases to lymph nodes and lungs, and only SPC produced a significant increase in tumor p53 expression. CONCLUSION: Taken together, these data suggest that the anti-prostate cancer activity of dietary soy protein, soy phytochemicals, and genistin use different molecular pathways. In addition, we have demonstrated that this animal model can be used in the design of dietary strategies for prostate cancer prevention and therapy.