Heterogeneity of Unilateral Multiple Breast Cancer: Implications for Biomarker Testing

Abstract

OBJECTIVE:This study was to re-examine the usefulness of biomarker assays in all multiple tumors in the same breast, and to evaluate the genetic heterogeneity of unilateral multiple breast carcinoma.MATERIALS AND METHODS:All of the cases met the criteria for synchronous multicentric breast carcinomas. Tumors were either 5 cm apart or within the different breast quadrants, with no identifiable connection between lesions, and were diagnosed at the same time for an individual patient.RESULTS:In the present study, 32 tumors from 15 patients with synchronous unilateral breast cancer were immunostained for estrogen receptor (ER), progesterone receptor (PR), and HER-2, and also underwent microsatellite analysis using 10 polymorphic markers. The ER and PR expression profile was similar in all tumors from the same patient. Discordant HER-2 immunoreactivity was found and confirmed by HER-2 FISH test in one case, and heterogeneity in the microsatellite pattern was observed in 6 patients.CONCLUSION:With the routinely-used biomarkers (ER, PR, and HER-2), heterogeneity was minimal, however, with more frequent differences noted at the genetic levels.