A 66-year-old male with bladder cancer underwent radical cystectomy and ileal conduit construction. The pathological diagnosis was urothelial carcinoma with squamous differentiation (pT3b). Computed tomography (CT) 18 months postoperatively revealed a right external iliac lymph node metastasis. He was treated with systemic chemotherapy after placement of bilateral ureteral stents, but CT following chemotherapy revealed an increase in the size of the metastasis, and the patient was diagnosed with progressive disease. Radiotherapy to the metastasis was selected as local therapy, but the patient was at risk of an uretero-arterial fistula because the right external iliac artery and the right ureter adjacent to the metastasis were involved in the irradiated field. The right external iliac lymph node metastasis was irradiated with a dose of 50 Gy after stent grafting for the right external iliac artery to prevent an ureteroarterial fistula. He had no adverse events, including hematuria after radiotherapy, but died of cancer cachexia 12 months after radiotherapy.