Abstract:

OBJECTIVE: To explore the molecular phenotypes of hormone receptor (HR，including ER and PR)-negative invasive breast cancers，and how the phenotypes relate to clinicopathologic features and prognosis. METHODS：Using tissue microarray (TMA) and immunohistochemistry (IHC) methods，according to the expression of HER2 and basal markers (CK5/6，CK14， EGFR)，the subtypes of these HR-negative breast cancers were classified as follows：basal-like (HER2?，any of the basal marker+)，HER2 (HER2+)，and null/unclassified (HER2?，all the basal marker?). The phenotype HER2 was subdivided into pure-HER2 (HER2+，all the basal marker?) and basal-HER2 phenotype (HER2+，any of the basal marker+). We summarized the associations between each phenotype and clinicopathologic parameters，and compared the mean survival across the IHC subtypes. RESULTS：HR-negative invasive breast cancers was more likely to be high-grade，late-stage，and disease onset close to menopause. But with no significant difference among various molecular phenotypes. Patients with basal-HER2 phenotype had significantly poorer 5-year disease-free survival and 5-year overall survival than with basal-like tumors (P <0 .05). CONCLUSION：Basal-like phenotype was not an independent prognostic factor. Basal-HER2 phenotype showed significantly poorer 5-year overall and disease-free survival than basal-like and all the non basal-HER2 phenotypes in HR-negative breast cancers.

Key words: HR-negative invasive breast cancers, molecular phenotypes, basal-like phenotype, basal-HER2 phenotype, prognosis