The expression of aldehyde dehydrogenase 1 in invasive primary breast tumors and axillary lymph node metastases is associated with poor clinical prognosis.

The enzyme aldehyde dehydrogenase 1 (ALDH1) has been reported as a biomarker for identifying cancer stem cells. Previous studies have shown that ALDH1 expression in primary breast cancers was associated with poor clinical prognosis. In this study, we aimed to determine whether ALDH1 expression in axillary lymph node metastases (ALNM) of breast cancer patients was also associated with poor prognosis. Expression of ALDH1, ER, PgR, HER2 and KI-67 was examined in primary tumors and ALNM of 161 patients with invasive breast cancer. Survival analysis and multivariate analysis were used to determine the relationship between ALDH1 expression and clinical prognosis. Patients with positive ALDH1 expression in primary tumors and in ALNM had significantly shorter relapse-free survival (RFS) times and overall survival (OS) times compared to those whose tissues were ALDH1 negative. ALDH1-positivity in primary tumors was significant both in univariate and multivariate analyses of RFS and OS. ALDH1 expression in ALNM was significant in a univariate analysis of RFS and OS but not in a multivariate analysis of RFS and OS. We conclude that the expression of ALDH1 in primary breast tumors or ALNM may be one potential risk factor for poor, long-term outcomes.