Objective: To study the expression and prognostic significance of ERG and SPINK1 expression in endocrine-treated prostatic cancer.
Methods: Prostatic needle biopsies from 118 prostatic cancer patients primarily treated with endocrine therapy were reviewed. Immunohistochemical study for ERG and SPINK1 protein was carried out.
Results: Co-expression of ERG and SPINK1 was not observed. The frequency of ERG protein expression in the 118 biopsies studied was 9.3% (11/118). The positive expression correlated with T stage (P=0.04) but not with patient age at diagnosis, prostatic specific antigen level, Gleason's score, M stage, tumor area and progression-free survival. Positive expression of SPINK1 was demonstrated in 11.0% (13/118) of the biopsies. SPINK1-positive cases carried a significantly shorter progression-free survival, as compared with SPINK1-negative cases (P=0.022). The expression was not associated with any other clinicopathologic variables. The following expression pattern showed statistically significant correlation with the clinical progress (P=0.029): ERG+/SPINK1- (11/118, 9.3%), ERG-/SPINK1+ (13/118, 11.0%) and ERG-/SPINK1- (94/118, 79.7%).
Conclusions: ERG and SPINK1 proteins are mutually exclusive.SPINK1 expression is associated with more aggressive clinical behavior and can serve as a prognostic biomarker in prostatic cancer.