Stanniocalcin-2 May Be a Potentially Valuable Prognostic Marker in Endometrial Cancer: a Preliminary Study

In the current study, we primarily aimed to investigate stanniocalcin-2 (STC₂) protein expression pattern in hysterectomy specimens from patients with endometrioid type endometrial cancer (EC) using immunohistochemistry. Secondly, in order to clarify its prognostic impact, we examined relationships of the expression levels of STC₂ with clinicopathologic features and outcome of patients. Histopathology slides of 49 patients were stained with the monoclonal mouse antibody targeting STC₂ protein. The expression levels of STC₂ were classified based on three-tiered semiquantitative scheme: negative expression, expression level of 0; low-expression, expression level of 1+; and high-expression, expression levels of 2+ and 3+. Recurrence-free survival (RFS) was used as the primary prognostic outcome. Immunohistochemical analysis revealed that 73.5% of tissue samples exhibited positive staining with STC₂. The intensity of staining with STC₂ was weak in 40.8%, moderate in 22.4%, and strong in 10.2%. Thirty-eight percent of samples showed negative expression; 18.4%, low-expression (1+); and 42.8%, high-expression (2 to 3+). High-expression of STC₂ was significantly associated with grade 2-3 tumors (p = 0.026) and disease recurrence (p = 0.013). Multivariate analysis revealed that both the tumor grade and STC₂ were independent predictors of disease recurrence. Kaplan-Meier analyses confirmed that patients with high-expression of STC₂ had a significantly poorer RFS than those with negative or low STC₂ expression (p = 0.037); although overall survival did not differ with respect to expression levels of STC₂ (p = 0.148). In conclusion, high-expression of STC₂ is a negative prognostic factor, associated with increased risk of recurrence in endometrioid EC.