SOX10 as a sensitive marker for triple negative breast cancer.

OBJECTIVE: Confirmation of breast origin for triple-negative breast cancer (TNBC) is sometimes problematic. Traditional breast markers GATA-binding protein 3 (GATA3), mammaglobin (MGB), and gross cystic disease fluid protein 15 (GCDFP15) showed limitation in identifying TNBC. Sry-related high-mobility-group/HMG box 10 (SOX10) has been proposed as a potential marker for TNBC. DESIGN: We analyzed and compared SOX10 with GATA3, MGB, and GCDFP15 expression in a testing cohort of 1,838 invasive breast cancer (IBC) using tissue microarray. The findings from the testing cohort was further examined with a validation cohort of 42 TNBC in whole sections. RESULT: The overall expression for SOX10, GATA3, MGB, and GCDFP15 were 6.9%, 83.1%, 47.0%, and 34.8%, respectively. Among the TNBC within this cohort, SOX10, GATA3, MGB, and GCDFP15 expression was 31.3%, 34.5%, 27.9%, and 25.2% respectively. SOX10 was strongly associated with TNBC (p < 0.001) whereas all other traditional markers were associated with non-TNBC (p < 0.001 for all). In addition, SOX10 was correlated with BLBC (p = .001) than five-markers negative subtype among the TNBC. High SOX10 (81%) expression was confirmed in the validation cohort. Additionally, SOX10 expression was inversely correlated with GATA3 and GCDFP15, thus they may complement each other in TNBC detection. SOX10-GATA3 combination yielded a sensitivity of 60.3% for TNBC detection in the test cohort. CONCLUSION: SOX10 is a reliable marker to identify TNBC, and complements GATA3. Combined SOX10-GATA3 may be used as a sensitive TNBC marker.