Stanniocalcin 2 expression is associated with a favourable outcome in male breast cancer

Breast cancer can arise in either gender; however, it is rare in men, accounting for <1% of diagnosed cases. In a previous transcriptomic screen of male and female breast cancer we observed that Stanniocalcin 2 (STC2) was overexpressed in the former. The aim of this study was to confirm the expression of STC2 in male breast cancer, and to investigate whether this had an impact on patient prognosis. Following an earlier transcriptomic screen, STC2 gene expression was confirmed by RT-qPCR in matched male and female BC samples as well as in tumour-associated fibroblasts derived from each gender. Subsequently, STC2 protein expression was examined immunohistochemically in tissue microarrays containing 477 male breast cancer cases. Cumulative survival probabilities were calculated using the Kaplan-Meier method and multivariate survival analysis was performed using the Cox hazard model. Gender-specific STC2 gene expression showed a 5.6-fold upregulation of STC2 transcripts in male breast cancer, also supported by data deposited in OncomineTM . STC2 protein expression was a positive prognostic factor for disease-free survival (Log rank; total p=0.035, HR=0.49; tumour cells p=0.017, HR=0.44; stroma p=0.030, HR=0.48), but had no significant impact on overall survival (Log rank; total p=0.23, HR=0.71; tumour cells p=0.069, HR=0.59; stroma p=0.650, HR=0.87). Importantly, multivariate analysis adjusted for patient age at diagnosis, node staging, tumour size, ER and PR status revealed that total STC2 expression as well as expression in tumour cells was an independent prognostic factor for disease-free survival (Cox regression; p=0.018, HR=0.983; p=0.015, HR=0.984 respectively). In conclusion STC2 expression is abundant in male breast cancer where it is an independent prognostic factor for disease-free survival. This article is protected by copyright. All rights reserved.