Prostate cancer represents a major contributor to cancer mortality, but the majority of men with prostate cancer will die of other causes. Thus, a challenge is identifying potentially lethal disease at diagnosis. Conflicting results have been reported when investigating the relationship between infiltration of lymphocytes and survival in prostate cancer. One of the mechanisms suggested is the recruitment of regulatory T cells (T regs ), a subpopulation of T cells that have a role in promoting tumor growth. T regs counteract tumor rejection through suppressive functions on the anti-immune response but their prognostic significance is still unknown. We report here the results of a conducted case-control study nested in a cohort of men treated with transurethral resection of the prostate and diagnosed incidentally with prostate cancer. Cases are men who died of prostate cancer (n ¼ 261) and controls are men who survived 410 years after their diagnosis (n ¼ 474). Infiltration of both T helper and T cytotoxic cells was frequently observed and the majority of the T regs were CD4 þ . T helper or T cytotoxic cells were not associated with lethal prostate cancer. However, we found a nearly twofold increased risk of lethal prostate cancer when comparing the highest with the lowest quartile of CD4 þ T reg cells (95% confidence interval: 1.3-2.9). Our conclusion is that men with greater numbers of CD4 þ T regs in their prostate tumor environment have an increased risk of dying of prostate cancer. Identification of CD4 þ T regs in tumor tissue may predict clinically relevant disease at time of diagnosis independently of other clinical factors.

BackgroundThe tumor promoting or counteracting effects of the immune response to cancer development are thought to be mediated to some extent by the infiltration of regulatory T cells (Tregs). In the present study we evaluated the prevalence of Treg populations in stromal and epithelial compartments of normal, post atrophic hyperplasia (PAH), prostatic intraepithelial neoplasia (PIN), and tumor lesions in men with and without prostate cancer.MethodsStudy subjects were 102 men consecutively diagnosed with localized prostate cancer undergoing radical prostatectomy and 38 men diagnosed with bladder cancer undergoing cystoprostatectomy without prostate cancer at the pathological examination. Whole mount sections from all patients were evaluated for the epithelial and stromal expression of CD4+ Tregs and CD8+ Tregs in normal, PAH, PIN, and tumor lesions. A Friedmańs test was used to investigate differences in the mean number of Tregs across histological lesions. Logistic regression was used to estimate crude and adjusted odds ratios (OR) for prostate cancer for each histological area.ResultsIn men with prostate cancer, similarly high numbers of stromal CD4+ Tregs were identified in PAH and tumor, but CD4+ Tregs were less common in PIN. Greater numbers of epithelial CD4+ Tregs in normal prostatic tissue were positively associated with both Gleason score and pT‐stage. We observed a fourfold increased risk of prostate cancer in men with epithelial CD4+ Tregs in the normal prostatic tissue counterpart.ConclusionsOur results may suggest a possible pathway through which PAH develops directly into prostate cancer in the presence of CD4+ Tregs and indicate that transformation of the anti‐tumor immune response may be initiated even before the primary tumor is established.

The ERG rearrangement is identified in approximately 50% of prostate cancer screened cohorts and is known to be highly specific. This genetic aberration, most commonly leading to the TMPRSS2-ERG fusion, but also SLC45A3-ERG or NDRG1-ERG fusions, all leading to an overexpression of a truncated ERG protein. Most studies have applied in situ hybridization (FISH) methods or mRNA-based assays to investigate the ERG status. Recently, studies showed that ERG protein levels assessed by ERG antibodies can be used as a surrogate marker for ERG rearrangement. In the current study, we investigate ERG status on a series of diagnostic biopsies using DNA-based, mRNA-based, and protein-based assays. We formally compared 3 assay results (ie, FISH, fusion mRNA, and immunohistochemistry) to identify which method could be most appropriate to use when having limited amount of tissue. ERG rearrangement was found in 56% of the cases. Comparing ERG rearrangement status by FISH with ERG overexpression and TMPRSS2-ERG fusion transcript we found 95.1% (154/162, Fisher exact test 9.50E-36) and 85.2% (138/162, Fisher exact test 7.26E-22) concordance, respectively. We show that the ERG antibody highly correlates with the ERG rearrangement with high sensitivity and specificity. We also identified the most common TMPRSS2-ERG isoform in the majority of ERG rearranged cases. These results provide compelling evidence that the ERG antibody can be used to further investigate the role of ERG in prostate cancer.