Prognostic Value of Pretreatment Serum Cystatin C Level in Nasopharyngeal Carcinoma Patients in the Intensity-modulated Radiotherapy Era

Purpose: Serum cystatin C has been considered as a significant prognostic factor for various malignancies. This study aimed to evaluate the relationship between serum cystatin C level before antitumor treatment and the prognosis of nasopharyngeal carcinoma (NPC) patients treated with intensity-modulated radiotherapy (IMRT). Patients and Methods: A cohort of 2077 NPC patients were enrolled between April 2009 and September 2012. The Kaplan-Meier curves and log rank tests were used to determine the differences of overall survival (OS) and disease-free survival (DFS). Univariate and multivariate Cox regression analyses were used to determine independent prognostic factors. Results: Overall, 362/2077 (17.4%) patients had high serum cystatin C level, and they were older and more male (both P<0.001), and they had higher TNM stage (all P<0.05). KaplanMeier analysis revealed that patients with high serum cystatin C had worse OS (P<0.001) and DFS (P<0.001). Univariate and multivariate Cox regression analysis showed that high serum cystatin C level was an independent prognostic predictor of OS (HR: 1.56, 95%CI: 1.25-1.95) and DFS (HR: 1.38, 95%CI: 1.13-1.68). Subgroup analysis based on TNM stage revealed that advanced-stage NPC patients with high serum cystatin C had poorer OS (P<0.001) and DFS (P<0.001). Conclusion: Our results revealed that high serum cystatin C level before antitumor treatment can predict clinical outcomes of NPC patients treated with IMRT, and it can guide clinicians to formulate more personalized therapy for NPC patients.