IntroductionSystemic anticancer therapy for locally advanced or metastatic urothelial carcinoma (la/mUC) is associated with efficacy benefits, including longer overall survival (OS), but many patients remain untreated. This observational, real-world, national study aimed to investigate factors associated with receiving systemic anticancer therapy for la/mUC in England. Patients and MethodsAdults diagnosed with la/mUC between 2013 and 2019 were identified in the National Cancer Registration Dataset and followed until March 2021. Healthcare and comorbidity data were obtained from Hospital Episode Statistics Admitted Patient Care and Outpatient datasets. Treatment data were obtained from the Systemic Anti-Cancer Therapy dataset. Factors associated with treatment were identified using multivariable logistic regression. OS from la/mUC diagnosis was estimated using Kaplan–Meier methodology. ResultsOf 16,610 patients diagnosed with la/mUC, 5,191 (31%) received systemic anticancer therapy; 4,700 (91%) received platinum-based chemotherapy. Only 18% of patients were cisplatin ineligible. Patients were significantly less likely to receive treatment if they were female, cisplatin ineligible, older, or diagnosed before 2018; had laUC, an Eastern Cooperative Oncology Group performance status >1, or greater comorbidity; or resided outside London or in income-deprived areas. Median OS (95% CI) from diagnosis in treated vs. untreated patients was 19.9 (19.4–20.6) vs. 5.8 (5.6–6.0) months, respectively. Limitations include retrospective analysis of data not initially collected for research purposes. ConclusionFrom 2013 to 2019, ≈70% of patients with la/mUC in England were untreated, which is high given the availability of effective treatments. Reasons for undertreatment should be addressed. Given the evolving treatment landscape, analysis of more recent data would be informative. MicroabstractThis study investigated systemic anticancer treatment for patients diagnosed with advanced urothelial carcinoma in England between 2013 and 2019. Of 16,610 patients, 31% received treatment. Various factors were associated with not receiving treatment, including female sex, older age, worse performance status, greater comorbidity, and resident in income-deprived areas. Median overall survival in treated vs. untreated patients was 19.9 vs. 5.8 months.