Prevalence of PD-L1 Expression in Patients With Advanced Urothelial Carcinoma

Inclusion Criteria: * Provision of written informed consent * Age ≥18 years old * Patient must have advanced UC confirmed by their HCP; histologically- confirmed diagnosis of UC an dHCP-confirmed advanced UC. * Patient must be either currently receiving 1L systemic treatment for their advanced UC or will be starting 1L systemic treatment (i.e. "newly diagnosed" advanced UC; 1L therapy is defined as the first systemic therapy given for advanced UC). * Patient remains eligible for the study if they received neoadjuvant or adjuvant platinum-based chemotherapy if their recurrence was more than 12 months after their last chemotherapy dose. * Radio-sensitizing chemotherapy as part of chemoradiation is NOT counted as neoadjuvant or adjuvant chemotherapy; thus, the 12-month interval mention above does not apply, and the patient would be eligible * Patients with available tumor tissue sample (fresh or archival - up to 3 years old) that was collected as part of SoC any time prior to 1L treatment for advanced UC with a target of 18 slides (7 minimum) available for biomarker testing (PD-L1 and tTMB). Already prepared slides must have been cut within 6 months prior to PD-L1 testing. Exclusion Criteria: * Patients concurrently enrolled in other clinical trials that prohibit their participation in a non-interventional study * Patient has resectable localized UC and has refused surgery * Patients with history of non-urothelial active malignancy that completed therapy within 2 years from study enrollment except: * Any resected in situ carcinoma or non-melanoma skin cancer * Localized (early stage) cancer treated with curative intent (without evidence of recurrence and intent for further therapy) and in which no systemic therapy was indicated