Renal cell carcinoma with level IV inferior vena cava tumor thrombus is rare and associated with high recurrence risk despite complete resection. We report an 80-year-old man who underwent radical nephrectomy and inferior vena cava thrombectomy with initial negative postoperative imaging. One year later, imaging findings were equivocal, but tumor-informed circulating tumor DNA was detectable, prompting early surgical resection of recurrent disease. Postoperatively, circulating tumor DNA became undetectable. This case highlights the potential role of tumor-informed circulating tumor DNA surveillance in detecting molecular residual disease and guiding management in high-risk renal cell carcinoma.

Non–muscle-invasive bladder cancer (NMIBC) with prostatic urethral involvement (PUI) is rare and difficult to manage, especially after intravesical therapy or pelvic radiation. We report a 78-year-old man with recurrent high-risk NMIBC and PUI after bacillus Calmette–Guérin and mitomycin C. Blue-light cystoscopy (BLC) during restaging identified additional carcinoma in situ and high-grade T1 disease not seen with white light. Histopathology showed no stromal invasion, and tumor-informed circulating tumor DNA (ctDNA) testing was negative, indicating no molecular residual disease. Despite favorable findings, the patient elected radical cystectomy, which revealed no residual tumor. This case highlights the complementary roles of BLC and ctDNA.