Many new biomarkers have been recently tested to enhance the accuracy of diagnosis, prediction of stage, estimation of metastatic potential and biochemical recurrence of PCa. So far, only a few have shown positive results and promising practical use in everyday practice. One of the most promising biomarkers is TMPRSS2:ERG gene fusion. This fusion is important not only for its high prevalence (or combining with other biomarkers), sensitivity and specificity in early diagnosis of PCa [7, 8], but also in predicting the stage [9–11], aggressiveness [9, 12] and metastatic potential of the tumor [11, 13].
In our study of 148 patients, we observed a prevalence of gene fusion in 42 %, which is similar to published data reporting prevalence ranges of 44–50 % [14–16]. Futhermore, we found no differences between fusion positive and negative cases in relation to age, PSA and GS. This is in concordance with the study by Magi-Galluzzi et al. that included 42 Caucasians, 64 African-Americans, and 44 Japanese patients who underwent radical prostatectomy . TMPRSS2:ERG gene fusion correlated with ethnicity (p = 0.03) and marginally correlated with pathologic stage (p = 0.06), but did not correlate with other clinicopathologic parameters, such as age, preoperative PSA levels, and GS. Pettersson et al.  did not find any statistical significance betveen TMPRSS2:ERG gene fusion and GS (either low grade or high grade). Their cohort study includes 1180 patients after radical prostatectomy. with 694 patients showing GS ≤ 7 and 355 with positive gene rearrangement; a total of 486 patients had poorly differentiated prostate carcinoma GS ≥8 and 229 patients had gene fusion (p = 0.58). Similarly, Perner et al.  did not observe any significant associations between GS and TMPRSS2:ERG status in their study of 118 patients.
Gopalan et al.  reported different results. The authors found a statistically significant correlation between gene fusion and low GS (p = 0.02). Gene fusion was found in 71 patients (32 %) with GS < 7, 118 patients (54 %) with GS = 7 and 16 patients (7 %) with GS > 7. Seventy-four patients (24 %) showed GS < 7, while 182 patients (60 %) with GS = 7 and 40 patients (13 %) with GS > 7 had no gene fusion.
In the study of Darnel et al.  of 196 patients, the authors found a statistically significant correlation between TMPRSS2:ERG gene fusion and lower primary Gleason pattern. Gene fusion was detected in 42 % of patients with primary Gleason pattern 3 and 27 % in primary Gleason pattern 4 (p = 0.014).
Demichelis et al.  showed a statistical significance between TMPRSS2:ERG gene fusion and higher GS (p = 0.01). Similar connections between gene fusion and GS ≥ 8 were shown in study by Font-Tello et al. .
The results of our study show a significant association between TMPRSS2:ERG gene fusion and pT stage. Perner S. et al.  reported high percentage of TMPRSS2:ERG rearrangements in patients with pT3 stage, i.e., 50/91 patients (55 %) and p = 0.03. Mehra et al.  reported similar findings for pT2b, but in the other direction. The authors found a statistically significant association between TMPRSS2 gene rearrangement and the presence of advanced pathologic tumour stage (p = 0.04), defining advanced stage as pT2b. In their study, a total of 24 out of 37 (65 %) patients with positive TMPRSS2 rearrangements had pathologic tumour stage ≤ pT2b. Font-Tello et al.  analyzed the mRNA levels of TMPRSS2-ERG, ERG, PTEN, and AR (n = 83), as well as ERG immunostaining (n = 78) in a series of prostate tumors. They found TMPRSS2:ERG gene fusion in 57 patients and it was associated with stage T3-T4 tumors. Saramäki et al.  did not find correlation between gene fusion and T3 stage (p = 1.0).
In our study TMPRSS2:ERG gene fusion was twice as frequent in the group of pT3 patients who did not undergo eLND compared with the group of pT3 patients who did undergo eLND. This finding indicates that we probably underestimate the group of patients with classical prognostic factors that characterise these patients as low or intermediate risk of PCa.
As we only had five patients with ERG split alone and three patients with both ERG split and TMPRSS2:ERG gene fusion, which was only 10 % of all gene rearrangements, the number of this subgroup was too small for statistical analyis.
Methodological differences in the patient cohorts could lead to these discrepancies. Some recent studies have shown that genetics diferences in prostate cancer among interracial groups can also be a reason for these discrepancies .
This study had several limitations. The study is retrospective in nature and prone to selection and collection bias. In addition, the sample size was fairly low, limiting subgroup data analyses. Therefore, all data should be confirmed in large possible prospective cohorts.
If confirmed in larger studies gene rearrangements on biopsies or postoperative specimens could be useful adjunct to clinical routine markers. In addition, it may be possible to detect these rearrangements in urine samples, eliminating the need for invasive specimen collection.