Combination of GATA3, SOX-10, and PAX8 in a Comprehensive Panel to Diagnose Breast Cancer Metastases.

BACKGROUND/AIM:It can be difficult to establish the origin of a tumor in metastatic breast cancer (MBC), especially with triple-negative breast cancer (TNBC) or high-grade features. We evaluated the diagnostic utility of GATA3, SOX10, and PAX8 panels in MBC by comparing their expression in each molecular subtype of MBC.PATIENTS AND METHODS:We evaluated 84 MBC and 37 primary TNBC cases using GATA3, SOX10, and PAX8 staining in whole tissue sections.RESULTS:GATA3 was least sensitive in the detection of metastatic TNBC (metastatic non-TNBC, 0.95; metastatic TNBC, 0.37). SOX10 had the lowest overall sensitivity (0.12) but was elevated in metastatic TNBC, even higher than GATA3 (0.59 vs. 0.37). The combination of GATA3, SOX10, and PAX8 expression showed the highest detection rate (MBC, 0.94; metastatic non-TNBC, 0.95; metastatic TNBC, 0.93).CONCLUSION:We recommend combining GATA3, SOX10, PAX8 expression profiling to confirm breast as the site of origin in metastatic MBC.