Evaluation of biomarkers in multifocal/multicentric invasive breast carcinomas

The purpose of this study was to evaluate whether breast carcinoma biomarkers vary among separate tumor foci of multifocal/multicentric (MF/MC) breast carcinomas and whether this variation correlates with morphological features and tumor grade.

We reviewed the biomarker profiles of MF/MC invasive breast carcinomas diagnosed between January 2001 and June 2010 at our institution. Estrogen receptor (ER), progesterone receptor (PR), and human epidermal receptor protein (HER2) results were classified as positive or negative.

Out of the 51 patients included in the study, 6 cases had 2 tumor foci with different morphologies, 7 cases had 2 foci with similar morphology but different grades, and 38 cases had 2 tumor foci with similar morphologies and grades. Out of the 38 patients who had MF/MC tumors with the same morphology and grade, only 1 patient had a difference in ER and PR status between foci. Out of the 7 patients who had morphologically similar tumors with different grades, 4 had similar results in both tumor foci, 3 had different results for ER and PR, and another had differing results for HER2 between the foci. All 6 patients who had MF/MC foci with different morphologies exhibited similar ER, PR, and HER2 results between the foci.

Regardless of the similarity in tumor morphology or grade, a small number of cases included foci that exhibited different tumor marker expression, which might affect the treatment strategy. Therefore, our results suggest that the evaluation of tumor markers in different foci should be considered in MF/MC tumors for accurate treatment strategies.