Reliability of small amounts of cancer in prostate biopsies to reveal pathologic grade

MUC1 Expression by Immunohistochemistry Is Associated with Adverse Pathologic Features in Prostate Cancer: A Multi-Institutional Study

Background

The uncertainties inherent in clinical measures of prostate cancer (CaP) aggressiveness endorse the investigation of clinically validated tissue biomarkers. MUC1 expression has been previously reported to independently predict aggressive localized prostate cancer. We used a large cohort to validate whether MUC1 protein levels measured by immunohistochemistry (IHC) predict aggressive cancer, recurrence and survival outcomes after radical prostatectomy independent of clinical and pathological parameters.

Material and Methods

MUC1 IHC was performed on a multi-institutional tissue microarray (TMA) resource including 1,326 men with a median follow-up of 5 years. Associations with clinical and pathological parameters were tested by the Chi-square test and the Wilcoxon rank sum test. Relationships with outcome were assessed with univariable and multivariable Cox proportional hazard models and the Log-rank test.

Results

The presence of MUC1 expression was significantly associated with extracapsular extension and higher Gleason score, but not with seminal vesicle invasion, age, positive surgical margins or pre-operative serum PSA levels. In univariable analyses, positive MUC1 staining was significantly associated with a worse recurrence free survival (RFS) (HR: 1.24, CI 1.03–1.49, P = 0.02), although not with disease specific survival (DSS, P>0.5). On multivariable analyses, the presence of positive surgical margins, extracapsular extension, seminal vesicle invasion, as well as higher pre-operative PSA and increasing Gleason score were independently associated with RFS, while MUC1 expression was not. Positive MUC1 expression was not independently associated with disease specific survival (DSS), but was weakly associated with overall survival (OS).

Conclusion

In our large, rigorously designed validation cohort, MUC1 protein expression was associated with adverse pathological features, although it was not an independent predictor of outcome after radical prostatectomy.

Nationwide prevalence of lymph node metastases in Gleason score 3 + 3 = 6 prostate cancer

Based on revisions of Gleason scoring in 2005, it has been reported that nodal metastases at radical prostatectomy in Gleason 3 + 3 = 6 (GS6) prostate cancer are extremely rare, and that GS6 cancers with nodal metastases are invariably upgraded upon review by academic urological pathologists. We analysed the prevalence and determinants of nodal metastases in a national sample of patients with GS6 cancer.We utilised the SEER database to identify patients diagnosed with GS6 prostate cancer during 2004-2010 who had radical prostatectomy and ≥1 lymph node(s) examined. We calculated the prevalence of nodal metastases and constructed a multivariable logistic regression model to identify factors associated with nodal metastases. Among 21,960 patients, the prevalence of nodal metastases was 0.48%. Older age, preoperative PSA >10  ng/mL, and advanced stage were positively associated with nodal metastases. Lymph node metastases in GS6 cancer are more prevalent in a nationwide population compared to academic centres. Revised guidelines for Gleason scoring have made GS6 cancer a more homogeneously indolent disease, which may be relevant in the era of active surveillance. We submit that lymph node metastases in GS6 cancer be used as a proxy for adherence to the 2005 ISUP consensus on Gleason grading.

Washout gradient in dynamic contrast-enhanced MRI is associated with tumor aggressiveness of prostate cancer

PURPOSE

To investigate the associations between dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) parameters and the Gleason score (GS) for prostate cancer (PCA) with localization information provided by concurrent apparent diffusion coefficient (ADC) maps.

MATERIALS AND METHODS

Forty-three male patients received MR scans, including diffusion tensor imaging (DTI) and DCE MRI, on a 1.5 T MR system. All patients were confirmed to have PCA in the following biopsy within 2 weeks. ADC maps calculated from DTI were used to colocalize cancerous and noncancerous regions on DCE MRI for perfusion analysis retrospectively. Semiquantitative parameters (peak enhancement, initial gradient, and washout gradient [WG] and quantitative parameters [K(trans) , ν(e) , and k(ep) ]) were calculated and correlated with the GS. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance of the perfusion parameters in assessing the aggressiveness of PCA.

RESULTS

A total of 41 PCA nodules were included in the analysis. Among all quantitative and semiquantitative parameters, only WG showed significant correlation with GS (r = -0.75, P < 0.0001). By defining tumor aggressiveness as a GS >6, WG demonstrated a good diagnostic performance, with the area under the ROC curve being 0.88. Under a cutoff point of WG = 0.125 min(-1) , the sensitivity and specificity were 0.87 and 0.78, respectively.

CONCLUSION

WG shows a significant association with GS and good diagnostic performance in assessing tumor aggressiveness. Therefore, WG is a potential marker of GS.

Prediagnostic Prostate-Specific Antigen Velocity and Probability of Detecting High-Grade Prostate Cancer

OBJECTIVES

Men with high-grade prostate cancer experience a survival benefit when androgen suppression therapy is combined with radiotherapy (RT) compared with RT alone. We evaluated whether an association exists between the pretreatment prostate-specific antigen (PSA) velocity and high-grade prostate cancer at diagnosis, controlling for known predictors of high-grade disease.

METHODS

The study cohort consisted of 358 men with Stage T1c-T4 prostate cancer treated with external beam RT from 1989 to 2002. Univariate and multivariate logistic regression analyses were used to assess whether an association exists between the pretreatment PSA velocity, PSA level, age, clinical T stage, and Gleason score 4+3 or greater compared with Gleason score 3+4 or less prostate cancer.

RESULTS

Of the 358 men, 73 had a Gleason score of 4+3 or greater. The median PSA velocity was 2.71 ng/mL/yr (interquartile range 1.09 to 12.6) for men with a Gleason score of 4+3 or greater and 1.24 ng/mL/yr (interquartile range 0.71 to 3.37) for men with a Gleason score of 3+4 or less. All clinical covariates were significantly associated (P < or = 0.05) with a Gleason score of 4+3 or greater on univariate analysis. On multivariate analysis, the PSA velocity (odds ratio 1.06, 95% confidence interval 1.02 to 1.10, P = 0.004), age (odds ratio 1.07, 95% confidence interval 1.02 to 1.13, P = 0.008), and clinical T stage (odds ratio 2.17, 95% confidence interval 1.21 to 3.92, P = 0.01) were significantly associated with the detection of Gleason score 4+3 or greater prostate cancer.

CONCLUSIONS

The prediagnostic PSA velocity, patient age, and clinical T stage were significantly associated with high-grade prostate cancer at diagnosis. Because a biopsy Gleason score of 4+3 or greater is associated with a prostatectomy Gleason score of 7 or greater in the vast majority of cases, these parameters can identify men at high risk of harboring occult high-grade prostate cancer, permitting improved selection of RT fields and the use of androgen suppression therapy.