ABSTRACT
INTRODUCTION: CA15-3 is a well-known tumour marker for breast cancer. Currently it is not recommended for screening or diagnosis of breast cancer and its main application is in monitoring response to treatment in women with metastatic breast cancer. The aim of this study was to correlate serum CA15-3 at presentation with the stage of disease and overall survival in women with breast cancer in the University Malaya Medical Centre. METHODS: This is a retrospective study of 437 women who had CA15-3 levels determined at initial presentation of breast cancer to UMMC between Jan 1999 and Oct 2003. RESULTS: Of those patients who were adequately staged, CA15-3 was found to be elevated (defined as >51 U/ml) in 0% of Stage 1, 7.9% of Stage 2, 36.7% of Stage 3 and 68.6% of Stage 4 cases. In a subset of 331 patients with survival data, patients with normal CA15-3 had a 85% five year overall survival rate compared to 38% in their counterparts with elevation of the tumor marker. The level of elevation was also significantly related to survival; patients with values more than 200 U/ml exhibited only a 28% five year survival. The association of elevated CA15-3 at initial presentation with poor outcome was maintained over univariate and multivariate analyses. CONCLUSION: Estimation of CA15-3 at presentation of breast cancer is important as it is an independent prognostic indicator and may prompt the physician to investigate for metastases if elevated.