Limited predictive impact of tumor size dynamics on further tumor shrinkage after 4 cycles of first-line chemotherapy in patients with advanced urothelial carcinoma

•Sequential treatment after cycle 4 in first line chemo for aUC is not standardized.•Only 16% of patients achieved further tumor shrinkage (>10%) with additional cycles.•Tumor size dynamics in cycles 1 to 4 did not fully predict further tumor shrinkage.•Early switch maintenance may be recommended for disease-controlled patients.