PURPOSE: This study sought to investigate the prognostic value of the autophagy 
marker microtubule-associated protein chain 3B (LC3B) in patients with residual 
tumors after neoadjuvant chemotherapy (NCT) for locally advanced breast cancer 
(LABC).
PATIENTS AND METHODS: The expression of LC3B in residual breast cancer cells was 
assessed by immunohistochemistry in surgical specimens from 229 patients 
diagnosed with histologically proven invasive breast cancer. All patients 
underwent NCT followed by mastectomy and were considered nonpathologic complete 
responders (non-pCR) after a pathologic evaluation. The prognostic value of 
various clinicopathologic factors was evaluated.
RESULTS: The LC3B density was similar between the peripheral and central area of 
the tumors (P = 0.328) but was significantly lower in the extratumoral area (P < 
0.001 and P < 0.001, respectively). Furthermore, LC3B density, which correlated 
with Beclin-1 expression, Ki-67 index, and breast cancer subtype, served as an 
independent prognostic factor for both relapse-free survival (RFS; P = 0.012) 
and overall survival (OS; P = 0.008); the prognostic value of LC3B was most 
significant in triple-negative patients. Using a combination of LC3B expression 
and the status of residual involved lymph nodes, the patients were classified 
into four groups with different risks of relapse and death (P < 0.001 for RFS 
and P = 0.003 for OS).
CONCLUSION: LC3B can be used as a prognostic marker in patients with non-pCR 
after NCT for breast cancer, which highlights the importance of autophagy in the 
biologic behavior of chemoresistant cancer cells. Furthermore, evaluating and 
targeting autophagy in the neoadjuvant setting may help prevent disease relapse 
in patients with non-pCR.