Expression of cancer stem cell markers in basal and penta-negative breast carcinomas--a study of a series of triple-negative tumors.

PURPOSE: Breast cancer is a heterogeneous disease. Immunohistochemistry has given rise to triple-negative carcinoma (TNC). Concomitantly, biological origins of neoplasia and its heterogeneity has been strongly debated in cancer stem cells (CSC) theme. This study investigates the prevalence of basal (BCC) and penta-negative carcinomas (5NC) in TNC and establishes associations with CSC (CD44CD24). MATERIALS AND METHODS: 94 TNC were tested for CK5/6, HER1, CD44 and CD24, evaluated by a simple immunohistochemistry score and correlated with clinicopathological and survival data. RESULTS: BCC had higher tumor grades than 5NC (p=0.004). CD44 negativity (p=0.007) and CD44(-)CD24(+) phenotype (p=0.013) were associated with less vascular invasion amongst TNC. CD44 expression was associated with BCC (p=0.007). CD44(-)CD24(-/low) phenotype was associated with 5NC. None of the variables were associated with clinical outcome. CONCLUSION: BCC and 5NC are closely related tumor subtypes. CD44(-)CD24(-/low) phenotype was associated with 5NC and CD44(-)CD24(+) phenotype was associated with vascular invasion. These results require histogenetic confirmation in larger studies.