Prognostic impact of doublecortin-like kinase 1 expression in locally advanced rectal cancer treated with preoperative chemoradiotherapy.

Preoperative chemoradiotherapy (CRT) is a standard therapy for locally advanced rectal cancer; however, the response varies depending on cases. Therefore, CRT-response predictors need to be elucidated. Cancer stem cells (CSCs), comprising a small part of tumors, are associated with tumor progression and recurrence due to their self-renewal and proliferation abilities. Doublecortin-like kinase 1 (DCLK1) is one of the several putative CSC markers; however, the clinical impact of its expression in rectal cancer has not been evaluated. The aim of this study was to clarify the clinical impact of DCLK1 expression in rectal cancer. We immunohistochemically evaluated DCLK1 expression in surgical specimens of 106 rectal cancer patients, including those who underwent preoperative CRT. The correlations between DCLK1 expression, and clinicopathological features and patient prognosis were then assessed. In rectal cancer patients treated with preoperative CRT, DCLK1 expression was significantly correlated with lymph node metastasis (p = 0.02) and poor cancer-specific survival (p = 0.049). However, in patients treated without preoperative therapy, no such correlation was found. DCLK1 expression can be associated with lymph node metastasis and poor cancer-specific survival in rectal cancer patients who receive CRT.