PURPOSETo investigate the safety and effectiveness of radiotherapy for advanced upper tract urothelial carcinoma (UTUC) patients intolerant to chemotherapy.METHODSData for 21 patients with advanced UTUC intolerant to chemotherapy were retrospectively collected. All patients were treated with conventionally fractionated radiotherapy (50-70 Gy/20-33 f) or partial-SABR boost to the lesions (50-60 Gy/20-25 f with tumor center boosted with 6-8 Gy/f, 3-5 f) for bulky tumors.RESULTSThe median age was 75 years (range, 58-87 years). Primary tumor resection was performed for all patients and none underwent metastatic resection. Seventeen (81%) patients had oligometastasis (1-5 metastases) at diagnosis. Eighteen (85.7%) received irradiation to all tumor lesions. Lymph node metastasis was predominant in the whole group (17/21). Other lesions were distributed as local recurrence (7/21), bone metastases (2/21) and abdominal wall/muscle (2/21). The median follow-up time was 38.5 months (interquartile range, 15.2-48.7 months). Rate of local control (LC), progression-free survival (PFS) and overall survival (OS) of the whole group at 1 year were 90%, 46.6%, and 80.4%, respectively. At 3 years, LC, PFS and OS were 65.6%, 26.6%, and 40.9%, respectively. Fourteen patients developed acute mild gastrointestinal toxicity, generally of grade 1-2; 8 patients developed acute grade 1-2 hematological toxicity, consisting mainly of anemia and leukopenia. No grade 3 or higher acute or late toxicities were observed.CONCLUSIONFor patients with advanced UTUC who are not able to tolerate chemotherapy, radiotherapy is a safe treatment and can achieve good local tumor control.