Expression of STIM1 is associated with tumor aggressiveness and poor prognosis in breast cancer.

STIM1 has been confirmed a key role involving in breast cancer proliferation and metastasis in vitro studies and its value in breast cancer patients is still to be defined. In this study, we investigate the correlation between STIM1 expressions with clinicopathologic features and prognosis quantified by disease-free survival (DFS) and overall survival (OS). To assess STIM1 expression, we conducted immunohistochemistry assays using breast cancer tissues encompassing a total of 165 breast cancer cases with detailed follow-up data and 40 cases of matched samples including cancer and adjacent normal tissues. STIM1 expression was present in 66.1% (109/165) of breast cancer cases which was significantly higher than adjacent non-tumor tissues. Larger tumors, lymphnode metastasis and negative estrogen receptor were positively associated with STIM1 overexpression. Furthermore, STIM1 expression was significantly associated with worse DFS (P=0.03) rather than OS in breast cancer patients.