OBJECTIVETo evaluate the classification and prognostic effects of a 2 cm tumor size in patients with ureteral cancer (UC) undergoing segmental ureterectomy (SU).PATIENTS AND METHODSA total of 75 patients with UC who underwent SU in our hospital between April 2013 and April 2023 were included in this study. The study population was grouped based on tumor size, which was defined as the maximum diameter of the pathological specimens, resulting in 30 patients (40.0%) with tumor size <2 cm and 45 patients (60.0%) with tumor size ≥2 cm. The clinicopathological variables, perioperative parameters, and oncological outcomes were compared between the 2 groups. The endpoints were recurrence-free survival (RFS), and cancer-specific survival (CSS).RESULTSA tumor ≥2 cm was related to a higher positive rate of urine exfoliative cytology (P = 0.049) and fewer preoperative ureteroscopies (P = 0.033) than tumors <2 cm. After a follow-up of 6.3 to 128.7 months (median 40.2 months), 23 cases (30.7%) experienced recurrence and 11 patients (14.7%) succumbed to UC in the end. Compared to those with tumor size <2 cm, patients with tumor size ≥2 cm experienced more urothelial recurrence (P = 0.032). Kaplan-Meier analysis demonstrated that patients with tumor size ≥2 cm displayed inferior urothelial RFS than those with tumor size <2 cm (P = 0.026). Multivariate Cox analysis identified tumor size ≥2 cm, and pathological stage ≥T2 were significant prognostic factors of poor urothelial RFS (all P < 0.05).CONCLUSIONTumor size ≥2 cm was associated with a high rate of urothelial recurrence and served as an independent prognostic factor of adverse urothelial RFS in SU-treated patients with UC. Patients are advised to select surgical treatments for UC following the EAU guidelines.