Role of autophagy-related protein expression in patients with rectal cancer treated with neoadjuvant chemoradiotherapy

Background: Autophagy, a cellular degradation process, has complex roles in tumourigenesis and resistance to cancer treatment in humans. The aim of this study was to explore the expression levels of autophagy-related proteins in patients with rectal cancer and evaluate their clinical role in the neoadjuvant chemoradiotherapy setting. Methods: All specimens evaluated were obtained from 101 patients with colorectal cancer who had undergone neoadjuvant chemoradiotherapy and curative surgery. The primary outcomes measured were the expression levels of two autophagy-related proteins (microtubule-associated protein 1 light chain 3 beta (LC3 beta) and beclin-1) by immunohistochemistry and their association with clinicopathological parameters and patient survival. Results: Among the 101 patients, the frequency of high expression of beclin-1 was 31.7 % (32/101) and that of LC3 beta was 46.5 % (47/101). A pathologic complete response was inversely associated with LC3 beta expression (P = 0.003) and alterations in the expression of autophagy-related proteins (P = 0.046). In the multivariate analysis, however, autophagy-related protein expression did not show prognostic significance for relapse-free survival or overall survival. Conclusions: High expression of autophagy-related proteins shows a strong negative association with the efficacy of neoadjuvant chemoradiotherapy in patients with rectal cancer. Autophagy has clear implications as a therapeutic target with which to improve the efficacy of neoadjuvant chemoradiotherapy.