C-erbB-2 onco-protein expression in breast cancer: relationship to tumour characteristics and short-term survival in Universiti Kebansaan Malaysia Medical Centre

Breast cancer is the commonest cancer affecting females in Malaysia, contributing 31% of all newly diagnosed cases amongst Malaysian women. The present retrospective cohort study evaluated the relationship between cerbB- 2 onco-protein overexpression with various tumour characteristics and survival rate of breast cancer patients treated at the Universiti Kebangsaan Malaysia Medical Centre (UKMMC) between 1996-2000. CerbB- 2 oncoprotein overexpression was determined by immunohistochemistry (IHC) and tumors showing 2+ positivity were verified by Fluorescence In Situ Hybridization (FISH). One hundred and seventy two patients were eligible for the study with a short-term follow-up (median) of 5.1 years. C-erbB-2 oncoprotein overexpression correlated with lymph node positivity, oestrogen receptor (ER) and progesterone receptor (PR) negativity. Univariate analyses showed shorter disease free survival (DFS) and overall survival (OS) in patients with cerbB- 2 oncoprotein overexpression, Malay ethnicity, higher tumour grade, lymph node positivity, ER and PR negativity. In a subgroup of patients with c-erbB-2 oncoprotein overexpression, a shorter OS was observed in those with lymph node positivity, ER and PR negativity. In multivariate prognostic analysis, lymph node status, ER status and tumour grading were the strongest independent prognostic factors for both OS and DFS. However, c-erbB-2 status was not a significantly independent prognostic factor, even in subsets with lymph node positive or negative group. C-erbB-2 oncoprotein overexpression correlated well with lymph node status, ER and PR. Shorter OS and DFS were significantly observed in patients with c-erbB-2 oncoprotein overexpression. Lymph node status, ER status and tumour grading were the only three independent prognostic factors for OS and DFS in this study. Although c-erbB-2 expression is obviously important from a biological standpoint, multivariate analysis showed that it is not an independent prognostic indicator in breast carcinoma in the local population.