Low/negative expression of DDX3 might predict poor prognosis in non-smoker patients with oral cancer

Objective: DDX3 has diverse biological functions in translation control, cell growth regulation, and tumor progression. Oral squamous cell carcinoma (OSCC) is a common malignant tumor worldwide with a poor clinical prognosis. The impact of DDX3 expression in OSCC is seldom discussed. Materials and Methods: Tumor tissues and adjacent normal tissues were obtained from 324 patients with OSCC. In this study, we used immunohistochemical staining methods to investigate the associations between DDX3 expression and the clinicopathological characteristics of OSCC. Results: Low/negative DDX3 expression in tumor cells was significantly associated OSCC patient characteristics including male gender (P <0.001), smoking (P <0.001), alcohol consumption (P <0.001), betel quid chewing (P = 0.002), poor relapse-free survival (P = 0.001), and poor overall survival (OS) (P = 0.001). Patients with low/negative DDX3 expression, and particularly non-smoker OSCC patients, had significantly worse OS as defined by the log-rank test (P = 0.020 for all cases; P = 0.008 for non-smoker patients). In non-smoker patients with OSCC, low/negative DDX3 expression in tumor cells was associated with poor prognosis (P = 0.024) and a 3.802-fold higher death risk, as determined by Cox regression. Conclusions: Low/negative DDX3 expression in tumor cells was significantly associated with aggressive clinical manifestations and might be an independent survival predictor, particularly in non-smoker patients with OSCC.