Studies examining the role of
signal transducer and activator of transcription 5 (STAT5) in various
cancers have produced controversial results. To address this controversy, we examined the prognostic role of STAT5a in
cancer patients across multiple
cancers. Transcription levels of STAT5a between
tumors and normal tissues, obtained from public databases, were analyzed for statistical differences using Cox regression analysis with the outcome as overall survival and covariate of interest as high STAT5a expression. Meta-analysis was then conducted to summarize the hazard ratio estimate from the Cox regression analyses. We found that STAT5a was significantly under-expressed in breast, lung, and
ovarian cancers, while STAT5a was significantly overexpressed in lymphoid
neoplasm diffuse large B-cell lymphoma,
glioblastoma, and
glioma. High STAT5a expression was significantly associated with favorable survival in
bladder cancer (lnHR = -0.8689 [-1.4087, -0.3292], P-value = 0.0016),
breast cancer (lnHR = -0.7805 [-1.1394, -0.4215], P-value < 0.0001) and
lung cancer (lnHR = -0.3255 [-0.6427, -0.0083], P-value = 0.0443). After adjusting for clinicopathological factors, high STAT5a expression remained significantly associated with favorable survival in
breast cancer (lnHR = -0.6091 [-1.0810, -0.1372], P-value = 0.0114). These results suggest that higher STAT5a expression is associated with favorable overall survival in
breast cancer, and therefore might have protective effects, and that STAT5a expression could be a potential prognostic
biomarker, especially in
breast cancer. However, the prognostic role of STAT5a is dependent on
cancer type.