Stereotactic Body Radiation Therapy in the Management of Oligometastatic and Oligoprogressive Bladder Cancer and Other Urothelial Malignancies

Aims: Bladder cancer represents the most common type of urothelial carcinoma, with a median overall survival of 12.5–15 months in the case of metastatic disease. We evaluated the role of stereotactic body radiation therapy (SBRT) in the management oligometastatic urothelial cancer. Materials and methods: Data on patients with a maximum of five metastases were collected from three institutions. Concomitant systemic therapy was allowed. End points were the local control of treated metastases, distant progression-free survival (PFS), overall PFS and overall survival. Results: Data for 82 lesions and 61 patients were included. The primary tumour was located in the bladder in 82% of patients, followed by kidney pelvis (11.5%). The most common treated site was lung (40.2%). Twenty-nine (47.5%) and 14 (23%) patients received systemic therapy before and during SBRT, respectively. The median BED10 value was 78.7 Gy. The median follow-up was 17.2 months. Rates of local control at 1 and 2 years were 92% and 88.9%, respectively, with correlation with systemic therapy before SBRT (hazard ratio 2.62, P = 0.034). Overall PFS at 1 and 2 years was 47.9% and 38.1%, respectively. The number of metastases was a predictive factor (hazard ratio 2.65, P = 0.008). The median overall survival was 25.6 months. Total dose (hazard ratio 0.93, P = 0.003) and BED10 (hazard ratio 0.97, P = 0.006) were correlated with overall survival. No grade ≥2 adverse events were reported. Conclusions: SBRT represents an effective and safe treatment in metastatic urothelial carcinoma. Prospective randomised trials are necessary to better evaluate the benefit on delaying the onset of new systemic therapies