PTEN losses exhibit heterogeneity in multifocal prostatic adenocarcinoma and are associated with higher Gleason grade.

Prostatic adenocarcinoma is an epithelial malignancy characterized by marked histological heterogeneity. It most often has a multifocal distribution within the gland, and different Gleason grades may be present within different foci. Data from our group and others have shown that the genomic deletion of the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) tumor suppressor gene and the disruption of the ETS gene family have a central role in prostate cancer and are likely to be associated with Gleason grade. In this study, prostate cancer samples were systematically analyzed to determine whether there was concordance between PTEN losses and TMPRSS2-ERG fusion rearrangements, within or between foci in multifocal disease, using well-annotated tissue microarrays (TMAs) consisting of 724 cores derived from 142 radical prostatectomy specimens. Three-color fluorescence in situ hybridization analysis of both the PTEN deletion and the TMPRSS2-ERG fusion was used to precisely map genetic heterogeneity, both within and between tumor foci represented on the TMA. PTEN deletion was observed in 56 of 134 (42%) patients (hemizygous=42 and homozygous=14). TMPRSS2-ERG fusion was observed in 63 of 139 (45%) patients. When analyzed by Gleason pattern for a given TMA core, PTEN deletions were significantly associated with Gleason grades 4 or 5 over grade 3 (P<0.001). Although TMPRSS2-ERG fusions showed a strong relationship with PTEN deletions (P=0.007), TMPRSS2-ERG fusions did not show correlation with Gleason grade. The pattern of genetic heterogeneity of PTEN deletion was more diverse than that observed for TMPRSS2-ERG fusions in multifocal disease. However, the marked interfocal discordance for both TMPRSS2-ERG fusions and PTEN deletions was consistent with the concept that multiple foci of prostate cancer arise independently within the same prostate, and that individual tumor foci can have distinct patterns of genetic rearrangements.

Perineural invasion on prostate biopsy does not predict adverse pathological outcome.

INTRODUCTION: The clinical significance of perineural invasion (PNI) on prostate needle biopsy is controversial. The aim of this present study is to determine the role of PNI on prostate biopsy in predicting adverse findings at radical prostatectomy in a recent cohort of screen detected prostate cancer. MATERIALS AND METHODS: We analyzed 470 patients diagnosed with prostate cancer from a prospectively maintained database at Princess Margaret Hospital. Out of the 470 patients diagnosed with prostate cancer, 139 underwent radical prostatectomy. Pathological specimens were examined, and perineural invasion was identified as carcinoma tracking along or around a nerve in the perineural space. We investigated the predictive value of PNI on biopsy with PNI on radical prostatectomy as well as the ability of PNI on prostate biopsy to predict adverse findings at radical prostatectomy. RESULTS: Perineural invasion was present in 124 (26%) of biopsy specimens diagnosed with prostate cancer and 94 (68%) of those who chose radical prostatectomy. Perineural invasion on prostate needle biopsy was not predictive of radical prostatectomy Gleason score (p = .377), pathological stage (p = .852), extraprostatic extension (p = .258), surgical margin (p = .079), lymphovascular invasion (p = .499), and upgrading (p = .514) or downgrading (p = .208) at radical prostatectomy. The sensitivity, specificity, positive predictive value, and negative predictive value of PNI on biopsy for PNI on radical prostatectomy were 32%, 82%, 79%, and 37% respectively. The Cohen's Kappa correlation coefficient was .11. CONCLUSIONS: Perineural invasion on prostate needle biopsy is not predictive of radical prostatectomy outcome. Furthermore, perineural invasion on biopsy has limited predictive value for perineural invasion at radical prostatectomy.

Accuracy of renal tumour biopsy for the diagnosis and subtyping of papillary renal cell carcinoma: analysis of paired biopsy and nephrectomy specimens with focus on discordant cases.

AIMS: Renal tumour biopsy (RTB) is increasingly recognised as a useful diagnostic tool in the management of small renal masses, particularly those that are incidentally found. Intratumoural heterogeneity with respect to morphology, grade and molecular features represents a frequently identified limitation to the use of RTB. While previous studies have evaluated pathological correlation between RTB and nephrectomy, no studies to date have focused specifically on the role of RTB for the diagnosis of papillary renal cell carcinoma (PRCC) and its further subclassification into clinically relevant subtypes. METHODS: This single-institution study evaluated 60 cases of PRCC for concordance between RTB and nephrectomy with respect to diagnosis, grading and subtyping (type 1/type 2). RESULTS: We observed 93% concordance (55 of 59 evaluable cases) between RTB and nephrectomy for the diagnosis of PRCC, although seven tumours (12%) were undergraded on RTB. Subtyping of PRCC on RTB was concordant with nephrectomy in 89% of cases reported as type 1 PRCC on RTB (31/35), but only 40% of cases reported as type 2 PRCC on RTB (4/10). Morphological misclassification of PRCC on RTB was most likely to occur in tumours showing a solid growth pattern. Discordant PRCC subtyping most often occurred in tumours with eosinophilia/oncocytic change. CONCLUSION: There was good concordance between RTB and nephrectomy for the primary diagnosis of PRCC. Although further subtyping of PRCC can aid therapeutic stratification, this can be challenging on RTB and tumours with overlapping or ambiguous features are best reported as PRCC not otherwise specified pending development of more robust methods to facilitate definitive subclassification.

An actionable sterol-regulated feedback loop modulates statin sensitivity in prostate cancer.

OBJECTIVE: The statin family of cholesterol-lowering drugs has been shown to induce tumor-specific apoptosis by inhibiting the rate-limiting enzyme of the mevalonate (MVA) pathway, HMG-CoA reductase (HMGCR). Accumulating evidence suggests that statin use may delay prostate cancer (PCa) progression in a subset of patients; however, the determinants of statin drug sensitivity in PCa remain unclear. Our goal was to identify molecular features of statin-sensitive PCa and opportunities to potentiate statin-induced PCa cell death. METHODS: Deregulation of HMGCR expression in PCa was evaluated by immunohistochemistry. The response of PCa cell lines to fluvastatin-mediated HMGCR inhibition was assessed using cell viability and apoptosis assays. Activation of the sterol-regulated feedback loop of the MVA pathway, which was hypothesized to modulate statin sensitivity in PCa, was also evaluated. Inhibition of this statin-induced feedback loop was performed using RNA interference or small molecule inhibitors. The achievable levels of fluvastatin in mouse prostate tissue were measured using liquid chromatography-mass spectrometry. RESULTS: High HMGCR expression in PCa was associated with poor prognosis; however, not all PCa cell lines underwent apoptosis in response to treatment with physiologically-achievable concentrations of fluvastatin. Rather, most cell lines initiated a feedback response mediated by sterol regulatory element-binding protein 2 (SREBP2), which led to the further upregulation of HMGCR and other lipid metabolism genes. Overcoming this feedback mechanism by knocking down or inhibiting SREBP2 potentiated fluvastatin-induced PCa cell death. Notably, we demonstrated that this feedback loop is pharmacologically-actionable, as the drug dipyridamole can be used to block fluvastatin-induced SREBP activation and augment apoptosis in statin-insensitive PCa cells. CONCLUSION: Our study implicates statin-induced SREBP2 activation as a PCa vulnerability that can be exploited for therapeutic purposes using clinically-approved agents.

Primary large cell neuroendocrine carcinoma of the urinary bladder.

Reports of primary large cell neuroendocrine carcinomas of the urinary bladder are few; we identified only 2 cases in the literature. Both of these cases involved male patients with rapid progression of disease culminating in death with widespread metastases. We report a case of primary large cell neuroendocrine carcinoma of the bladder, with an admixed minor element of adenocarcinoma, in an 82-year-old man. This solitary lesion arose in a bladder diverticulum lateral to the left ureteric orifice. Two attempts at transurethral resection were unsuccessful at achieving local control. The patient underwent a partial cystectomy with left-sided pelvic lymphadenectomy following preoperative staging investigations that found no metastatic disease. Pathologically, the tumor invaded into the deep aspect of the muscularis propria, without extension into perivesical fat. The lateral resection margin was microscopically positive for tumor, but no malignancy was found in the pelvic lymph nodes. The adenocarcinoma comprised less than 5% of total tumor volume, and areas of transition between the neuroendocrine and adenocarcinoma components were apparent. The patient developed a local recurrence 8 months postoperatively, which was managed by a combination of transurethral resection and radiation therapy. Currently, the patient has no evidence of local or metastatic disease 2 years after initial diagnosis.

Correlation of the primary Gleason pattern on prostate needle biopsy with clinico-pathological factors in Gleason 7 tumors.

OBJECTIVES: To correlate the primary Gleason pattern among patients with biopsy-derived Gleason 7 tumors with the radical prostatectomy specimen Gleason grading and other clinical and pathologic outcomes. METHODS AND MATERIALS: Among 474 patients who underwent radical prostatectomy for clinically localized prostate cancer between 1997-2001, 205 (43%) had Gleason 7/10 tumors on pre-operative needle biopsy. Among theses patients, 148 (72.2%) were assigned a primary Gleason 3 pattern (3+4 = 7) and 57 (27.8%) were assigned a primary Gleason 4 pattern (4+3 = 7). The two groups were compared with respect to age, serum PSA levels, Gleason grade in the radical prostatectomy specimen, pathological stage and surgical margin status. RESULTS: Among patients with 3+4 tumors on needle biopsy, 64% remained primary Gleason grade 3 while 35% were up-graded to a primary pattern 4 following analysis of the radical prostatectomy specimen. Patients with 4+3 tumors on needle biopsy remained primary Gleason grade 4 in 51% of patients, while 49% of patients had their tumors down-graded to a primary 3 pattern (p = 0.09). There were no differences between patients with needle biopsy 3+4 and 4+3 patterns with respect to total Gleason score in the radical prostatectomy specimen (p = 0.42), pTNM stage (p = 0.36), extra-prostatic extension (p = 0.88), surgical margin involvement (p = 0.16), and seminal vesicle invasion (p = 0.19). In contrast, the primary Gleason pattern in the radical prostatectomy specimen correlated significantly with pTNM stage (p = 0.02) and seminal vesicle invasion (p= 0.003), but not with extra-prostatic extension (p = 0.32) and surgical margin involvement (p = 0.17). CONCLUSIONS: Among patients with Gleason 7 adenocarcinoma of the prostate, the biopsy-derived primary Gleason pattern does not appear to correlate with important clinical and pathologic outcomes. The utility of distinguishing a primary Gleason pattern on needle biopsy among patients with Gleason 7 tumors remains unclear given the limited and conflicting literature addressing this issue.

MRI and contrast-enhanced ultrasound monitoring of prostate microwave focal thermal therapy: an in vivo canine study.

PURPOSE: To compare the value of diffusion-weighted MRI (DWI), dynamic contrast-enhanced (DCE) MRI, and microbubble contrast-enhanced ultrasound (CEUS) for assessment of the thermal lesion created by interstitial microwave heating of the normal canine prostate. MATERIALS AND METHODS: A microwave antenna was inserted into each lobe of the prostate in seven dogs to induce coagulation necrosis. Immediately after therapy the lesion was assessed using CEUS, DCE-MRI, and DWI. The prostates were excised, photographed, and prepared for hematoxylin and eosin staining. Results from posttreatment MRI and ultrasound were compared to histology. RESULTS: The apparent diffusion coefficient (ADC) was slightly lowered within the thermal lesion but was drastically reduced in a ring-like region that corresponds to a grossly appearing red thermal damage zone immediately peripheral to the central coagulum. Both DCE-MRI and CEUS delineated a smaller area of vascular damage, for which the borders lie within the red zone. CONCLUSION: The red zone encompasses a range of vascular responses, including hyperemia and hemostasis, and is known to progress to necrosis and tissue nonviability. DWI clearly depicts this zone as a region of sharply reduced ADC, and may be better than contrast-enhanced imaging for accurate assessment of the eventual full extent of thermal damage.

Interobserver variability between expert urologic pathologists for extraprostatic extension and surgical margin status in radical prostatectomy specimens.

Accurate Gleason score, pathologic stage, and surgical margin (SM) information is critical for the planning of post-radical prostatectomy management in patients with prostate cancer. Although interobserver variability for Gleason score among urologic pathologists has been well documented, such data for pathologic stage and SM assessment are limited. We report the first study to address interobserver variability in a group of expert pathologists concerning extraprostatic soft tissue (EPE) and SM interpretation for radical prostatectomy specimens. A panel of 3 urologic pathologists selected 6 groups of 10 slides designated as being positive, negative, or equivocal for either EPE or SM based on unanimous agreement. Twelve expert urologic pathologists, who were blinded to the panel diagnoses, reviewed 40x whole-slide scans and provided diagnoses for EPE and SM on each slide. On the basis of panel diagnoses, as the gold standard, specificity, sensitivity, and accuracy values were high for both EPE (87.5%, 95.0%, and 91.2%) and SM (97.5%, 83.3%, and 90.4%). Overall kappa values for all 60 slides were 0.74 for SM and 0.63 for EPE. The kappa values were higher for slides with definitive gold standard EPE (kappa=0.81) and SM (kappa=0.73) diagnoses when compared with the EPE (kappa=0.29) and SM (kappa=0.62) equivocal slides. This difference was markedly pronounced for EPE. Urologic pathologists show good to excellent agreement when evaluating EPE and SM. Interobserver variability for EPE and SM interpretation was principally related to the lack of a clearly definable prostatic capsule and crush/thermal artifact along the edge of the gland, respectively.

The continuing importance of transrectal ultrasound identification of prostatic lesions.

PURPOSE: In light of a recent tendency toward systematic nontargeted biopsy we reassessed whether identification and biopsy of ultrasonographically suspicious lesions contribute to the detection of prostate cancer. MATERIALS AND METHODS: We reviewed prospectively gathered data on 7,426 transrectal ultrasound directed prostatic biopsies performed at our institution between June 16, 2000 and September 1, 2005. Patients underwent systematic biopsy (6 to 10 cores on initial biopsy and 13 to 15 on rebiopsy) with additional sampling of visible suspicious lesions. The RR for finding cancer in transrectal ultrasound positive and negative patients was calculated for likely independent prognostic variables. RESULTS: A total of 3,828 biopsies (51.5%) were transrectal ultrasound negative and 3,598 (48.5%) were transrectal ultrasound positive. Prostate cancer was detected in 3,258 biopsies (43.9%). For each independent variable the RR for prostate cancer was higher if a sonographic lesion was present. A lesion increased the likelihood of cancer detection (57.8% vs 30.8%, RR 1.8). Biopsies from lesions identified by transrectal ultrasound had a greater median percent of the core involved with cancer (50% vs 10%, p <0.001) and they were more likely to have Gleason score 7 or greater (69.3% vs 28.3%, p <0.001). CONCLUSIONS: Biopsies taken when a prostatic lesion is identified by transrectal ultrasound are almost twice as likely to show cancer than when no lesion is visible. These cancers are of higher grade and volume and, therefore, they are more clinically significant. The search for and targeted biopsy of suspicious lesions seen on transrectal ultrasound remains important for prostate cancer diagnosis.

The uncertainty of radio frequency treatment of renal cell carcinoma: findings at immediate and delayed nephrectomy.

PURPOSE: Radio frequency thermal therapy for the ablation of renal cell carcinoma has been reported. Outcomes are usually measured by imaging alone. We have performed ex vivo and in vivo experiments using radio frequency in porcine models in our laboratory. We now report our early experience in the treatment of renal cell carcinoma in patients who underwent post-radio frequency radical or partial nephrectomy. MATERIALS AND METHODS: We treated 10 patients diagnosed with small renal masses with radio frequency. All masses were biopsied before treatment. In 4 patients 5 renal cell carcinomas were treated with radio frequency after surgical exposure of the tumor followed immediately by partial or radical nephrectomy (acute group). Six other patients were treated percutaneously with ultrasound or computerized tomography guided radio frequency under local anesthesia and intravenous sedation 7 days before partial or radical nephrectomy (delayed group). A median of 2 radio frequency cycles was applied. Mean total heating time was 17 minutes 15 seconds. Specimens were analyzed grossly and histologically. Triphasic contrast-enhanced computerized tomography and/or magnetic resonance imaging was performed before and 7 days after radio frequency treatment in the delayed group. RESULTS: Mean radiological largest diameter of all 11 masses was 2.4 cm. and mean gross diameter was 2.2 cm. Pathological examination demonstrated residual viable tumor in approximately 5% of the volume in 4 of the 5 tumors in the acute group and in 3 of the 6 masses of the delayed group. In 1 delayed case the viable tumor appeared to be in contact with the renal vein. No significant complications were observed in 9 of the 10 patients. In 1 delayed case, a subcapsular hepatic hematoma, biliary fistula and pneumonia developed and resolved. CONCLUSIONS: Based on our experience, we continue to consider percutaneous radio frequency for the treatment of small renal cell carcinomas as a potentially curative therapy. However, complete tumor cell death appears to be difficult to achieve with our current treatment protocol. More phase II testing is indicated to ensure that this technique is an effective and reproducible treatment alternative.