Co-expression of ER-beta and HER2 associated with poorer prognosis in primary breast cancer

Purpose: To assess the prognostic value of co-expression of estrogen receptor (ER)-beta and human epidermal growth factor receptor 2 (HER2) in primary breast cancer patients in China. Methods: Tumour specimens from 308 patients undergoing surgery for primary breast cancer were evaluated. Expression of ER-beta and HER-2 was investigated by the immunohistochemistry. Results: 123 patients (40%) were ER-beta positive and 58 (18.5 %) were HER2 positive. Among the 58 HER2 positive patients, 44 were ER-beta positive and 14 were ERbeta negative. ER-beta positive was associated with HER2 positive (75.9%, P=0.018) as well as ER-alpha positive (79.7%, P=0.023), poor cell differentiation (77.2% grade 2 or 3, P=0.010) and menopause age < 45 yr (55.3%, P=0.031). HER2 positive was associated with poor cell differentiation (93.1%, P=0.001), >= 3cm tumour size (67.2%, P=0.011). Conclusion: Both ER-beta positive and HER2 positive status was associated with poorer overall survival (OS) by univariate analysis. In both HER2 positive and HER2 negative subgroups, ER-beta positive was associated with poorer distant disease free survival (DDFS) but not OS, which implied that ER-beta might relate to metastasis in breast cancer.