This study was a prospective, open-label, phase II randomised controlled clinical study, enrolling patients with primary oligometastatic uroepithelial carcinoma, oligometastasis was defined as ≤3 organs, and the number of metastatic lesions and size of metastases were not restricted to be able to satisfy the definition of full-coverage radiotherapy, with the exception of patients with brain metastases and more than 3 liver metastases.

If regional lymph node recurrence was present, all positive regional lymph nodes were collectively referred to as one lesion. Non-regional lymph node metastases were counted as the number of metastases by lymph node subregion.

Patients were divided into two groups according to whether they received radiotherapy or not: 1) systemic therapy group; 2) systemic therapy + radiotherapy group. Systemic drug therapy can be chosen from chemotherapy or immune checkpoint inhibitor therapy, or combination therapy.

This study was a prospective, open-label, phase II randomised controlled clinical study, enrolling patients with primary oligometastatic uroepithelial carcinoma, oligometastasis was defined as ≤3 organs, and the number of metastatic lesions and size of metastases were not restricted to be able to satisfy the definition of full-coverage radiotherapy, with the exception of patients with brain metastases and more than 3 liver metastases.

If regional lymph node recurrence was present, all positive regional lymph nodes were collectively referred to as one lesion. Non-regional lymph node metastases were counted as the number of metastases by lymph node subregion.

Patients were divided into two groups according to whether they received radiotherapy or not: 1) systemic therapy group; 2) systemic therapy + radiotherapy group. Systemic drug therapy can be chosen from chemotherapy or immune checkpoint inhibitor therapy, or combination therapy.

Inclusion Criteria:

• Patients with metastatic uroepithelial cancer with histologically confirmed diagnosis (pathologically confirmed primary focus or one of the metastatic foci is sufficient) (metastasis after total cystectomy, metastasis after full-length nephroureteral resection, or metastatic uroepithelial cancer of the pelvic-ureteral bladder at the first diagnosis of inoperable metastatic uroepithelial cancer).
• Oligometastases were defined as ≤3 organs, and the number and size of metastatic lesions were not restricted to the extent that full-coverage radiotherapy could be met. If regional lymph node recurrence was present, all positive regional lymph nodes were collectively referred to as one lesion. Non-regional lymph node metastases are counted as metastases by lymph node subregion.
• Willing and able to provide written informed consent/assent for the trial; age ≥18 years on the date of signing the informed consent form and patient age ≤80 years.
• Expected survival time ≥ 6 months;
• Eastern Collaborative Oncology Group (ECOG) Physical Status (PS) score of 0 to 1;
• Normal major organ function, i.e., the following criteria are met: routine blood tests: a) Haemoglobin ≥ 90 g/L; b) Total bilirubin ≤ 2 x upper limit of normal (ULN); c) Aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) ≤ 2.5 x ULN in the absence of liver metastases, and ALT, AST and ALP ≤ 5 x ULN in the presence of liver metastases; d) Creatinine clearance (CrCl) ≥30 mL/min;

Exclusion Criteria:

• Pathological type non-urothelial carcinoma;
• Patients with brain metastases and >3 liver metastases; patients with spinal bone metastases at risk of spinal cord compression; patients with pericardial, pleural or abdominopelvic fluid;
• Patients who are intolerant to or have had a reduction in systemic therapy; patients with tumour progression assessed after 2 cycles of systemic therapy.