Evaluation of SOX10 Immunohistochemical Expression in Mammary Carcinoma

Abstract Background Invasive breast cancer (IBC) is the most frequent malignant neoplasm of female patients accounting for around 25% of all recorded cases globally. IBC is classified into five molecular subtypes. Triple-negative breast carcinoma (TNBC) are IBCs that lack expression of all three routine biomarkers; namely ER, PR, and Her2neu, it forms about 15-25 % of all IBCs. TNBC is characterized by its high degree of aggressiveness and greater recurrence and metastasis rates. Metastatic TNBC might be challenging to distinguish from other metastatic adenocarcinoma that are ER, PR, and Her2neu negative. Other sensitive & specific immunohistochemical markers are required to help distinguish primary from metastatic carcinomas, especially TNBC. Recently Sox10 has been suggested to be regularly expressed in primary breast cancers, particularly basal-like breast cancers and metaplastic TNBC. Objective This is primarily to evaluate the immunohistochemical expression of SOX-10 in invasive breast cancer in general and its expression in triple-negative breast cancers (TNBC) compared to other molecular subtypes. Methods This retrospective study included 62 TNBC cases and 21 non-TNBC cases. The immunohistochemical expression of Sox10 was tested, evaluated, and compared in different study groups with subsequent statistical analysis. Results Sox10 expression was positive in 39 cases of TNBC (92.9%) compared to only 3 cases of non-TNBC (7.1%). The SOX10 expression was significantly expressed in TNBC (p > 0.001). This expression was more frequent in TNBC compared to non-TNBC (p-value < 0.001). Moreover, Sox10 was more frequently expressed in TNBC than other molecular subtypes of primary breast cancer (p- value = 0.001). Conclusions Sox10 is more highly expressed in TNBC than other molecular subtypes of non-TNBC. It may represent a potentially valuable diagnostic marker for other hormone receptor-negative tumors in the metastatic setting.