Characteristics of HER-2/neu Oncogene in Korean Women with Early-onset Breast Cancer by Immunohistochemistry and Fluorescence In Situ Hybridization / 한국유방암학회지

ABSTRACT

PURPOSE: The purpose of this work was to investigate the prognostic significance of of HER-2/neu (HER-2) oncogene protein overexpression in Korean women with early-onset breast cancer by immunohistochemistry. Furthermore, the results of the test were correlated with HER-2 oncogene gene amplification assessed by fluorescence in situ hybridization (FISH). METHODS: HER-2 status in 60 cases of breast cancer diagnosed at the age of 45 years or younger was investigated by a rabbit polyclonal antibody (Dako) and by applying the Hercep Test, and the results were compared with FISH analysis in all Hercep Test 2+ and 3+ specimens (28 cases) and five HER-2/neu negative specimens. RESULTS: FISH revealed that HER-2 was exclusively amplified in cases with Hercep Test 3+ (20/21). Cases with Hercep Test 3+ or FISH positive tumors were significantly associated with estrogen and progesterone receptor negative tumors. No association was found between HER-2 status and axillary node status. In univariate analysis, FISH status was significantly associated with poor prognosis, but Hercep Test status was not a significant prognostic factor. CONCLUSION: The finding of higher positive tumors and poor prognostic factor of Her-2 in Korean women with early- onset breast cancer may have potential implication for local and systemic management of breast cancer. HER-2 test may be useful for selecting systemic chemotherapy in Korean patients with early onset breast cancer. And the specific anti-HER-2 therapy will be helpful to a large proportion of Korean patients who have more tumors with HER-2 overexpression than White patients.