Expression of cancer stem cell markers (CD24, CD44 & ALDH1A3 isoform) in Breast Cancer in Indian population considering clinicopathological characteristics and response to neoadjuvant chemotherapy - a prospective analysis from a university hospital.

Cancer stem cells (CSC) are a small number of tumour propagating cells present in the bulk of tumour cells. Expression of biological markers for CSCs viz. cluster of differentiation 24 and 44 (CD24, CD44) and aldehyde dehyodeganse 1 (ALDH1) imply aggressive tumour cell behaviour and poorer outcome, particularly in breast cancer. N = 75 Tumor tissue samples from enrolled breast cancer patients were obtained and subjected to histopathological examination and immunohistochemistry (IHC) after informed consent from patients. In addition to the estrogen receptor, progesterone receptor, Her2 neu receptor, and Ki67 index; IHC was also performed for CD24, CD44 and ALDH1A3 expression. These markers' positivity was correlated with clinical parameters, therapy response and metastasis prognostication. Most patients had higher tumor stage and high nodal burden (81.3% with node positivity; N1-68%, N2 -6.6%, N3-6.6%). Study showed significant association of CD24-/CD44 + group (p = 0.021) with distant metastasis and significant association of CD24-/CD44 + /ALDH1A3 + (p = 0.008) with higher stage (T4 stage). Tumor tissues expressing CD24-/CD44 + /ALDH1A3 + group (p = 0.010) and CD24 + /CD44 + / ALDH1A3 + (p = 0.010) were significantly associated with poor response to treatment. The correlation of CD24-/CD44 + was also statistically significant (p = 0.009). Positive expression of either CD24 and/or CD44 presented with aggressive disease, larger tumours and heavy nodal burden at a younger age. Additionally, ALDH1A3 positivity signified higher metastasis rates. CD24-/CD44 + /ALDH1A3 + and CD24 + /CD44 + / ALDH1A3 + correlated with greater chances of distant metastasis, aggressive disease, limited response to chemotherapy and poorer prognosis. Thus, these observations establish the role of these CSC phenotypes as important factors for prognostic outcomes and predictors of adverse outcomes. CD24-/CD44 + /ALDH1A3 + expression could serve as an important prognostic marker and predictor of adverse outcomes in Indian breast cancer tumour biology.