Aldehyde dehydrogenase 1 (ALDH1) and sex determining region-Y-related high mobility group box 2 (SOX2) have been identified as putative
cancer stem-like cell/tumor-initiating cell markers in various
cancer tissues. The aim of this study was to elucidate the prognostic impact of these putative
cancer stem-like cell/tumor-initiating cell markers in upper urinary tract urothelial cell
carcinoma. Immunohistochemical staining for ALDH1 and SOX2 was carried out on archival specimens from 125 patients with upper urinary tract urothelial cell
carcinoma who underwent radical
nephroureterectomy. The prognostic value of ALDH1 and SOX2 expression and other clinicopathological features was evaluated. On univariate analysis,
tumor grade, pathological T stage, pathological N stage, lymphovascular invasion, ALDH1 expression and SOX2 expression were associated with a poor prognosis. On multivariate analysis, the independent factors of prognosis were
tumor grade (P=0.014), pathological N stage (P=0.005) and ALDH1 expression (P=0.002). In subgroup analysis, those subgroups with no positive, one positive or two positive results in immunohistochemistry for ALDH1 and SOX2 expression had estimated 5-year
cancer-specific survival rates of 80%, 49% and 22%, respectively (P<0.001). Neither ALDH1 nor SOX2 expression correlated with intravesical recurrence after radical
nephroureterectomy. These findings suggest that
cancer stem-like cells/tumor-initiating cells are linked to more aggressive behavior of upper urinary tract urothelial cell
carcinoma, supporting the current cancer stem cell hypothesis. Thus, therapeutic targeting of
cancer stem-like cells/tumor-initiating cells in upper urinary tract urothelial cell
carcinoma is a future possibility.