41 Clinical Utility of Ultrasensitive ctDNA Detection Across the Renal Cell Carcinoma Disease Spectrum: A Multi-Cohort Retrospective Study - Ezra Blumenthal; Paulo Siqueira do Amaral; Yi Chen; Charles Abbott; Richard Chen; Kelvin Moses; Kerry Schaffer; Scott Haake; Brian Rini; Alan Tan (The Oncologist, 2026)