Introduction & Objectives

We previously compared ERG and PTEN protein expression in systematic biopsies with radical prostatectomy (RP) findings. MRI-Ultrasound (MRI-US) guided biopsies are expected to more accurately reflect the biological changes in the RP specimens. Here, we studied the correlation of PTEN and ERG status in MRI-US fusion biopsies (FBx) and RP specimens, and assessed the predictive value of FBx on disease stage and grade at RP.

Material & Methods

The study included patients who had undergone RP in Helsinki University Hospital between June 2015 and May 2017, and had preoperative FBx tissue available (n=110). Matched FBx specimens and tissue microarrays constructed from RP were immunostained with ERG and PTEN antibodies, and scored as either negative or positive. The RP TMA contained one to three clinically relevant cancer foci per patient.

Results

A high correlation of both PTEN and ERG status was observed between FBx and RP materials (Table 1). The correlation of PTEN status was particularly better compared with our previous findings in systematic 12-core biopsies (Lokman et al. 2017), where there was no significant concordance. High grade RP (grade group 4&5) correlated with ERG negativity in FBx (p=0.021), whereas PTEN was lost in high stage RP (pT≥3) to a higher extent than in low stage RP (pT2, p= n.s). Higher FBx grade group was associated with stage increase in RP (p=0.014).

Conclusions

FBx is feasible method to assess ERG and PTEN status correctly in RP specimens. More validation studies, accompanied with MRI features, are warranted.

Table 1A. Concordance of ERG IHC status in fusion biopsies (FBx) and radical prostatectomy (RP) specimens.

 RP ERG Negative RP ERG Positive P-value 
FBx ERG Negative 54 (90.0) 6 (10.0) <0.001a 
FBx ERG Positive 3 (7.1) 39 (92.9)  
    
Table 1B. Concordance of PTEN IHC (Any PTEN Loss) status in FBx and RP specimens. 
 RP Any PTEN Loss RP PTEN Intact P-value 
FBx Any PTEN Loss 14 (73.7) 5 (26.3) 0.002a 
FBx PTEN Intact 22 (32.4) 46 (67.6)  
    
Table 1C. Concordance of PTEN IHC (Complete PTEN Loss) status in FBx and RP specimens. 
 RP Complete PTEN Loss RP PTEN Intact P-value 
FBx Complete PTEN Loss 6 (50.0) 3 (50.0) <0.001a 
FBx PTEN Intact 3 (4.0) 72 (96.0)  
aFisher''s exact test. All p-values two-tailed. 
 RP ERG Negative RP ERG Positive P-value 
FBx ERG Negative 54 (90.0) 6 (10.0) <0.001a 
FBx ERG Positive 3 (7.1) 39 (92.9)  
    
Table 1B. Concordance of PTEN IHC (Any PTEN Loss) status in FBx and RP specimens. 
 RP Any PTEN Loss RP PTEN Intact P-value 
FBx Any PTEN Loss 14 (73.7) 5 (26.3) 0.002a 
FBx PTEN Intact 22 (32.4) 46 (67.6)  
    
Table 1C. Concordance of PTEN IHC (Complete PTEN Loss) status in FBx and RP specimens. 
 RP Complete PTEN Loss RP PTEN Intact P-value 
FBx Complete PTEN Loss 6 (50.0) 3 (50.0) <0.001a 
FBx PTEN Intact 3 (4.0) 72 (96.0)  
aFisher''s exact test. All p-values two-tailed. 

Citation Format: Andrew Erickson, Utku Lokman, Kanerva Lahdensuo, Sara Tornberg, Harri Visapää, Robin Bergroth, Henrikki Santti, Anssi Petas, Tuomas Mirtti, Antti Rannikko. PTEN and ERG expression in MRI-ultrasound guided fusion biopsy correlated with radical prostatectomy findings in men with prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4602.