Purpose: To investigate the association of pretreatment Ki67 expression and the derived neutrophil–lymphocyte ratio (dNLR) with clinical outcomes in nasopharyngeal carcinoma (NPC). 
Patients and methods: For the study, 46 patients diagnosed with NPC at our hospital were recruited between April 2013 and December 2015. All patients were histologically confirmed to have non-keratinizing undifferentiated NPC. The expression of Ki67 proteins in NPC tissue was analyzed immunohistochemically, and the dNLR was assessed in the peripheral blood, both before treatment. Stage I and II disease was treated with radiotherapy with or without concurrent chemotherapy, and stage III and IV disease was treated with cisplatin-based radiochemotherapy and neoadjuvant chemotherapy regimens. 
Results: Forty-five of the 46 patients met the criteria, and the median follow-up period was 41 months (15–56 months). The cutoff values for Ki67 and dNLR were 77.5% and 2.01%, respectively. The 3-year overall survival (OS) and progression-free survival rates in the high versus low Ki67 expression groups were 62.5% vs. 93.1% (P = 0.009) and 56.3% vs. 93.1% (P = 0.003), respectively. The 3-year OS rate of patients with high dNLR vs. low dNLR was 64.3% vs. 90.3% (P = 0.023). In the Cox risk ratio model, Ki67 expression and dNLR were independent prognostic factors for OS. Patients were then divided into three groups based on Ki67 expression and dNLR (high risk, both factors were high; intermediate risk, one factor was high; and low risk, neither factor was high). The 3-year OS rates were 20%, 85%, and 95% for the high, intermediate, and low risk groups, respectively (P < 0.001).
Conclusion: Pretreatment Ki67 and dNLR levels can be used as independent prognostic markers in NPC, and elevated values are associated with poor prognosis. Concurrently, high Ki67 expression and dNLR predict a significantly adverse outcome.
Keywords: nasopharyngeal carcinoma, Ki67, dNLR, prognosis