RecruitingPhase 2Drug trialPhotodynamic Diagnosis of Upper Tract Urothelial Carcinoma Using Fluorescence Endoscopy and Oral 5-ALAThis study is evaluating whether a medication called 5-aminolevulinic acid (5-ALA), approved by the FDA for use in brain surgery, can help improve the visibility of upper tract urothelial tumors during surgery. Patients undergoing ureteroscopic tumor resection will receive 5-ALA prior to surgery, and surgeons will use special blue light to help identify abnormal tissue that might not be seen under standard white light. The goal is to assess whether this technique can enhance tumor detection and removal.