Grosset AA, Ouellet V, Caron C, et al. - Researchers evaluated two various multi-center tissue microarrays (TMAs) from cohorts of individuals (Test-TMA and Validation-TMA series) of the Canadian Prostate Cancer Biomarker Network (CPCBN) to verify the correlation between p65 nuclear frequency and prostate cancer (PC) outcomes. Immunohistochemical staining of p65 was conducted on the Test-TMA and Validation-TMA series, which involved PC tissues from those treated by first-line radical prostatectomy (n = 250 and n = 1,262, respectively). The frequency of p65 in the nucleus of prostate cancer cells was an independent prognosticator of biochemical recurrence (BCR) using continuous and dichotomized data, as seen in multivariate analysis of the Validation-TMA cohort. This biomarker also correlated with the development of bone metastases and PC-specific mortality, independent of clinical parameters via a cutoff of 3%. For individuals with higher p65 nuclear frequency, BCR-free survival, bone-metastasis-free survival, and PC-specific survival were lower. In conclusion, this was the first study that used the pan-Canadian multi-center cohorts of CPCBN and confirmed the relationship between the higher frequency of nuclear p65 frequency and the risk of disease progression.