Decreased expression of light chain 3 (LC3) increased the risk of distant metastasis in triple-negative breast cancer.

The aim of this study was to evaluate the prognostic value of light chain 3 (LC3) expression in triple-negative breast cancer (TNBC) and describe the association of LC3 expression with the occurrence of metastasis. LC3 expression in tissue microarray was evaluated by immunohistochemistry in 163 patients with TNBC. The prognostic value of LC3 expression was assessed by a Cox regression model adjusted for clinical characteristics. Low LC3 expression in TNBC was observed in 56 (34.4 %) of 163 TNBC. Low LC3 expression significantly correlated with a higher risk of distant metastasis, rather than locoregional relapse. The 10-year distant metastases-free survival for LC3-negative and LC3-positive patients was 57.2 and 95.1 %, respectively (p < 0.0001). Accordingly, a significant correlation was found between LC3 expression and disease-free survival (DFS) and overall survival (OS). Multivariate analysis indicated that LC3 negative was a significant independent prognostic factor of DFS (p = 0.019), but not for OS (p = 0.545) in all patients. Our results suggested that expression of LC3 in TNBC was associated with higher distant metastases. This finding could open new avenues for the development of novel therapy strategies to TNBC.