Influence of Comorbidity on the Risk of Mortality in Men With Unfavorable-Risk Prostate Cancer Undergoing High-Dose Radiation Therapy Alone

E-Cadherin Downregulation is Mediated by Promoter Methylation in Canine Prostate Cancer

E-cadherin is a transmembrane glycoprotein responsible for cell-to-cell adhesion, and its loss has been associated with metastasis development. Although E-cadherin downregulation was previously reported in canine prostate cancer (PC), the mechanism involved in this process is unclear. It is well established that dogs, besides humans, spontaneously develop PC with high frequency; therefore, canine PC is an interesting model to study human PC. In human PC, CDH1 methylation has been associated with E-cadherin downregulation. However, no previous studies have described the methylation pattern of CDH1 promoter in canine PC. Herein, we evaluated the E-cadherin protein and gene expression in canine PC compared to normal tissues. DNA methylation pattern was investigated as a regulatory mechanism of CDH1 silencing. Our cohort is composed of 20 normal prostates, 20 proliferative inflammatory atrophy (PIA) lesions, 20 PC, and 11 metastases from 60 dogs. The E-cadherin protein expression was assessed by immunohistochemistry and western blotting and gene expression by qPCR. Bisulfite- pyrosequencing assay was performed to investigate the CDH1 promoter methylation pattern. Membranous E-cadherin expression was observed in all prostatic tissues. A higher number of E-cadherin negative cells was detected more frequently in PC compared to normal and PIA samples. High-grade PC showed a diffuse membranous positive immunostaining. Furthermore, PC patients with a higher number of E-cadherin negative cells presented shorter survival time and higher Gleason scores. Western blotting and qPCR assays confirmed the immunohistochemical results, showing lower E-cadherin protein and gene expression levels in PC compared to normal samples. We identified CDH1 promoter hypermethylation in PIA and PC samples. An in vitro assay with two canine prostate cancer cells (PC1 and PC2 cell lines) was performed to confirm the methylation as a regulatory mechanism of E-cadherin expression. PC1 cell line presented CDH1 hypermethylation and after 5-Aza-dC treatment, a decreased CDH1 methylation and increased gene expression levels were observed. Positive E-cadherin cells were massively found in metastases (mean of 90.6%). In conclusion, low levels of E-cadherin protein, gene downregulation and CDH1 hypermethylation was detected in canine PC. However, in metastatic foci occur E-cadherin re-expression confirming its relevance in these processes.

The risk of prostate cancer mortality and cardiovascular mortality of nonmetastatic prostate cancer patients: A population-based retrospective cohort study

PURPOSE

To assess the risk of prostate cancer (PCa) specific mortality (PCSM) compared to cardiovascular disease mortality (CVDM), or other-cause mortality (OCM) of men with nonmetastatic PCa according to PCa risk groups, primary treatment, and age.

PATIENTS AND METHODS

This retrospective population-based cohort study identified 1,908 nonmetastatic PCa patients in the cancer registry Zurich and Zug, diagnosed between 2000 and 2009 living in the City of Zurich. Multiple imputation methods were applied to handle missing PCa information. Fine and Gray competing risk regression analysis was used to estimate subdistribution hazard ratios for the outcomes PCSM, CVDM, or OCM RESULTS: Ten years after diagnosis the cumulative probability of PCSM and CVDM was 16.4% and 10.0%, respectively. We observed an increased adjusted risk of PCSM in men treated with androgen deprivation therapy (ADT) compared to surgery, but could not observe an association between ADT and CVDM. The probability of PCSM was significantly higher for patients on active surveillance or watchful waiting, compared to surgery. Age and PCa risk categories were positively associated with risk of PCSM, whereas there was no evidence for an association with CVDM or OCM based on risk groups.

CONCLUSIONS

Overall, men with PCa were more likely to die from non-PCa related outcomes. Nevertheless, the analyses showed a high proportion of PCSM among men on ADT, older men and men with a high-risk tumor. However, further research is needed to understand comprehensively the benefits of the respective treatments.

Brachytherapy monotherapy may be sufficient for a subset of patients with unfavorable intermediate risk prostate cancer

PURPOSE/OBJECTIVE(S)

Brachytherapy (BT) monotherapy is a well-established treatment modality for favorable intermediate risk (FIR) prostate cancer. However, patients with unfavorable intermediate risk (UIR) disease are often recommended trimodality therapy involving BT, androgen deprivation therapy (ADT), and external beam radiation therapy (EBRT). We sought to investigate the relative benefit of supplemental therapies (ADT and/or EBRT) for FIR and UIR prostate cancer in a large dataset.

MATERIALS/METHODS

We identified 3,723 patients with intermediate risk prostate cancer treated with BT between 1997 and 2013, including 1,989 and 1,734 patients with FIR and UIR disease, respectively. For the FIR cohort, Fine and Gray's competing risks regression model was used to evaluate whether there was a difference in prostate cancer specific mortality (PCSM) between BT vs. BT + supplemental therapy (ADT, EBRT, or both). For the UIR cohort, this regression model was used to evaluate whether supplemental ADT, EBRT, or both decreased PCSM beyond BT alone. Both regression models were adjusted for clinical and treatment-related factors.

RESULTS

The median follow-up periods were 7.7 years (interquartile range: 5.4-10.5) for the FIR cohort and 7.8 years (interquartile range: 5.3-10.6) for the UIR cohort. For the FIR cohort, there was no difference in PCSM between BT monotherapy vs. BT + supplemental therapy (adjusted hazard ratio [AHR] = 1.70; 95% CI: 0.46-6.29; P = 0.43). For the UIR cohort, supplemental EBRT (AHR = 2.66; 95% CI: 1.12-6.34; P = 0.03), ADT (AHR = 0.96; 95% CI: 0.38-2.43; P = 0.93), or both (AHR = 1.46; 95% CI: 0.42-5.01; P = 0.55) were not associated with improved PCSM compared with BT alone.

CONCLUSION

In our analysis, supplemental therapies did not offer an improvement in PCSM compared with BT alone for FIR or UIR prostate cancers. Further prospective clinical trials are required to determine whether BT monotherapy may be sufficient for a subset of patients with UIR disease.