Relationships between plasma fibrinogen and prognosis and tumor metastasis in patients with nasopharyngeal carcinoma

Objective To investigate the relationships between the plasma fibrinogen level before treatment and prognosis and tumor metastasis in patients with nasopharyngeal carcinoma. Methods The clinical data of 817 patients with non-distant metastasis nasopharyngeal carcinoma from January 2005 to October 2014 in our hospital were collected. All the patients were followed up, and the median follow-up time was 37.6 months. The critical value of plasma fibrinogen before treatment was determined by receiver operating characteristic (ROC) curve. The overall survival (OS) and distant metastasis free survival (DMFS) and their relevant factors were analyzed by Kaplan-Meier and Cox regression model. Results The critical value of plasma fibrinogen before treatment was 3.314 g/L determined by ROC curve analysis. The plasma fibrinogen level before treatment was related to the TNM stage (χ2=6.048, P=0.014), T stage (χ2=13.764, P<0.001) and distant metastasis after treatment (χ2=14.637, P<0.001). Survival analysis showed that the 3-year OS rate and 3-year DMFS rate in patients with plasma fibrinogen level ≥3.314 g/L before treatment were significantly lower than those in patients with plasma fibrinogen level <3.314 g/L, with significant differences (87.2% vs. 95.6%, χ2=4.562, P<0.001; 71.1% vs. 82.2%, χ2=5.153, P<0.001). Cox multivariate analysis showed that high level of plasma fibrinogen before treatment (HR=1.961, 95%CI: 1.332-2.917, P=0.001), EB virus DNA (HR=1.929, 95%CI: 1.275-2.849, P=0.001) and pretreatment stage (HR=1.653, 95%CI: 1.013-2.709, P=0.045) were the independent influencing factors of OS. The high level of plasma fibrinogen before treatment (HR=1.519, 95%CI: 1.142-1.964, P=0.002) and EB virus DNA (HR=1.950, 95%CI: 1.483-2.555, P<0.001) were the independent influencing factors of DMFS. Of the 817 patients, 179 patients (21.91%) had metastasis during the follow-up period, and 159 patients (88.83%) had metastasis within 3 years after treatment. The plasma fibrinogen level before treatment in 638 patients without metastasis (3.197±1.009) was significantly lower than that in 179 patients with metastasis (3.351±1.042; t=5.089, P=0.024), and was significantly lower than that in 87 patients with bone metastasis (3.430±1.004; t=6.752, P=0.009), 68 patients with pulmonary metastasis (3.301±1.018; t=4.281, P=0.039) and 71 patients with liver metastasis (3.413±1.107; t=6.398, P=0.011). Conclusion The plasma fibrinogen level before treatment can be used as an independent index to predict the prognosis of patients with nasopharyngeal carcinoma, which is related to tumor metastasis. Key words: Fibrinogen; Nasopharyngeal neoplasms; Metastasis; Prognosis