This study aimed to further validate the prognostic role of fibrinogen in upper tract urothelial carcinoma (UTUC) in a large Chinese cohort.A total of 703 patients who underwent radical nephroureterectomy were retrospectively identified.Fibrinogen levels of ≥4.025 g l-1 were defined as elevated.Logistic regression analysis was performed to determine the association between fibrinogen and adverse pathological features.Kaplan-Meier analysis and Cox regression models were used to assess the associations of fibrinogen with cancer-specific survival (CSS),disease recurrence-free survival (RFS),and overall survival (OS).Harrell c-index and decision curve analysis were used to assess the clinical utility of multivariate models.The median follow-up duration was 42 (range:1-168) months.Logistic regression analysis revealed that elevated fibrinogen was associated with higher tumor stage and grade,lymph node involvement,lymphovascular invasion,sessile carcinoma,concomitant variant histology,and positive surgical margins (all P < 0.05).Multivariate Cox regression analysis demonstrated that elevated fibrinogen was independently associated with decreased CSS (hazard ratio [HR]:2.33;P < 0.001),RFS (HR:2.09;P < 0.001),and OS (HR:2.09;P < 0.001).The predictive accuracies of the multivariate models were improved by 3.2%,2.0%,and 2.8% for CSS,RFS,and OS,respectively,when fibrinogen was added.Decision curve analysis showed an added benefit for CSS prediction when fibrinogen was added to the model.Preoperative fibrinogen may be a strong independent predictor of worse oncologic outcomes in UTUC;therefore,it may be valuable to apply this marker to the current risk stratification in UTUC.