CA9 and breast cancer: The objectives of this study were to investigate the immunohistochemical expression of G-CSF in a large series of breast cancers powered for correlation with clinicopathological features, CAIX expression, and immune checkpoint biomarkers; and to examine the prognostic significance of G-CSF in relation to CAIX and CD163+ M2 macrophages using breast cancer-specific survival as the primary endpoint, and overall survival and relapse-free survival as secondary endpoints.