Notably, breast cancer tissue strong for ALDH1A1 expression displayed weak NOTCH1 staining compared to ALDH1A1 weak tumor tissue (P = 0.002), and the relationship between ALDH1A1 and NOTCH1 mRNA positivity was significant (Pearson correlation - 0.337, P = 0.014; Spearman’s rho - 0.376, P = 0.006). This evidence concerns the gene ALDH1A1 and breast cancer.