Comparison of HER-2 overexpression in primary breast cancer and metastatic sites and its effect on biological targeting therapy of metastatic disease

• Published in: British journal of cancer 2005-09, Vol.93 (5), p.552-556
• Main Authors: Zidan, J, Dashkovsky, I, Stayerman, C, Basher, W, Cozacov, C, Hadary, A
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Breast Neoplasms - genetics; Breast Neoplasms - metabolism; Breast Neoplasms - pathology; Cancer Research; Carcinoma, Ductal, Breast - genetics; Carcinoma, Ductal, Breast - metabolism; Carcinoma, Ductal, Breast - pathology; Carcinoma, Lobular - genetics; Carcinoma, Lobular - metabolism; Carcinoma, Lobular - pathology; Drug Resistance; Epidemiology; Female; Gynecology. Andrology. Obstetrics; Humans; Immunoenzyme Techniques; In Situ Hybridization, Fluorescence; Male; Mammary gland diseases; Medical sciences; Middle Aged; Molecular Diagnostics; Molecular Medicine; Neoplasm Metastasis - pathology; Neoplasm Staging; Oncology; Prognosis; Receptor, ErbB-2 - metabolism; Tumors
• ISSN: 0007-0920; 1532-1827
• DOI: 10.1038/sj.bjc.6602738

HER-2 overexpression, a predictive marker of tumour aggressiveness and responsiveness to therapy, occurs in 20–30% of breast cancer. Although breast cancer is a heterogeneous disease, HER-2 measurement is carried out in primary tumour. This study aims to evaluate HER-2 overexpression in primary and metastases and its effect on treatment decisions. Biopsies from primary breast cancer and corresponding metastases from 58 patients were studied. HER-2 overexpression was evaluated immunohistochemically in all primary and metastatic sites. Positive overexpression in primary and/or metastases was confirmed by fluorescence in situ hybridisation (FISH). Discordance in HER-2 overexpression between primary and metastatic sites was 14% (eight of 58 patients). Concordance was found in 50 (86%) of patients (95% CI: 77–95). In one patient (2%), HER-2 was negative in metastasis but positive in primary. In seven (12%) patients, HER-2 was positive in metastases and negative in primary (95% CI: 3.7–20), and three of them responded to trastuzumab. Gene amplification by FISH was found in all cases with HER-2 positive (+2 and +3) by immunohistochemistry. Our data suggest that a possible discordance of HER-2 overexpression between primary and metastases should be considered when making treatment decisions in patients with primary HER-2-negative tumours.