Purpose: Kidney cancer has been increasing 1.7% annually. Renal cell carcinoma is the most common kidney cancer and it can metastasize. Our aim was to analyze patients treated with stereotactic body radiation therapy of renal cell carcinoma metastases.
Materials and methods: A total of 58 patients (73 lesions) were treated from 2004 to 2016. Patients were candidates for analysis if a maximum of 3 metastases were diagnosed and the primary tumor was resected. Toxicity was classified according to Common Terminology Criteria for Adverse Events version 3.
Results: All patients had renal cell carcinoma, in particular the clear cell type in 82.7%. A total of 39 metastases (53.4%) were located in the lungs and 19 (26%) were in the lymph nodes. Less common were metastases to bone (9.5% of cases), the liver (4.1%) and the adrenal gland (6.8%). Median followup was 16.1 months (range 3.5 to 157.1). The local control rate at 12 and 18 months was 90.2% and 90.2%, respectively. The progression-free survival rate at 12 and 18 months was 46.2% (95% CI 32.2-59) and 35% (95% CI 21.4-48.9), respectively. On univariate and multivariable analyses metachronous and single metastases predicted better progression-free survival. Systemic therapy before stereotactic body radiation therapy predicted improved local control in clear cell cases.
Conclusions: Stereotactic body radiation therapy can be considered a safe approach and it provides effective local control of oligometastatic renal cell carcinoma. However, future prospective studies are necessary to evaluate the impact on survival and quality of life.