ALDH1 and tumor infiltrating lymphocytes as predictors for neoadjuvant chemotherapy response in breast cancer

Many studies have reported that Aldehyde dehydrogenase 1 (ALDH1) and tumor-infiltrating lymphocytes (TIL) are related to breast cancer prognosis. However, the clinical significance of ALDH1 and tumor-infiltrating immune cells in breast cancer has not been fully investigated in patients who received neoadjuvant chemotherapy (NAC). We studied the significance of the expression of ALDH1 and the population of TIL for predicting the prognosis and chemotherapeutic response of patients with breast cancer who had received NAC. Forty patients who underwent NAC were enrolled in this study. ALDH1 and TIL (T cells and tumor associated macrophages) were evaluated before and after NAC. The influences of ALDH1 expression status and TIL populations on both prognosis and chemotherapeutic response were evaluated. ALDH1 positivity was related to estrogen receptor (p = 0.026) and progesterone receptor negativity (p = 0.025). Positive change of ALDH1 after NAC tended to be associated with a poor NAC response (p = 0.078). Patients with more CD8+ T cells before NAC and fewer CD68 (+) macrophages after NAC tended to have better OS, respectively (p = 0.086, p = 0.096). The chemotherapeutic response and prognosis of patients with breast cancer who received NAC are thought to be determined by the tumor microenvironment. Further research with more patients and a longer study period is needed.