O PAPEL PROGNÓSTICO DAS CÉLULAS INICIADORAS TUMORAIS (CIT) NO CÂNCER DE MAMA.

Abstract

Breast cancer is the second most common cancer in the world. It is a complex and heterogeneous disease with diverse clinical features, cellular origin, histological types, mutations, prognosis and therapeutic possibilities. A subpopulation of cells with the ability of self-renewing, increased proliferation and resistance to chemotherapy has been described in breast cancer, named tumor-initiating cells (TICs). The aim of this study was to review and integrate, through meta-analysis, the studies that have investigated the possible associations between tumor-initiating cells, defined by CD44+ CD24- low phenotype and ALDH expression, by using immunohistochemistry, and prognostic aspects of breast cancer. Twenty studies met the inclusion criteria for this meta-analysis, 13 evaluated the CD44+ CD24- low phenotype, 11 evaluated the expression of ALDH and four studies evaluated both markers. The results of the metaanalysis demonstrated statistically significant associations between the triple negative phenotype and the CITs, including both the expression of CD44+ CD24- low phenotype (p < 0.0001), as the expression of ALDH (p = 0.0004). Associations investigated for HER2 overexpression presented conflicting results, whereas CD44+ CD24- low phenotype was not significantly associated with this parameter (p = 0.1989), ALDH expression was significantly associated with HER2 (p < 0.0001). An inverse association, however, statistically significant, was observed between the presence of lymph node metastases and CD44+ CD24- low phenotype (p = 0.0047), while the expression of ALDH was not significantly associated with this parameter (p = 2019). Based on the analyses carried out, it can be concluded that the markers, CD44+ CD24- low and ALDH, represent an important tool in identifying tumor initiating cells in breast carcinomas and that statistical associations observed in this study raise important perspectives for developing molecular therapies based on presence of the CD44+ CD24- low phenotype and ALDH expression in the treatment of triple-negative breast carcinomas.