ERBB2 and cancer: When combining the cases having luminal B (HER2+/ER+) and HER2+/ER- subtypes, coexpression of HSP90 and PI3K-p110α or expression of HSP90 along with PTEN loss demonstrated strong prognostic significance in terms of RFS in patients with HER2-positive cancers, but not with HER2-negative cancer.