The efficacy of stereotactic radiotherapy for metastases from renal cell carcinoma

Our purpose was to evaluate the efficacy of stereotactic radiotherapy (SRT) for intracranial and extracranial metastases in patients with renal cell carcinoma. The retrospective analysis of 85 patients (151 tumors) treated with SRT was performed. SRT was the sole treatment in 35% of tumors, the other 65% had received additional treatment such as surgery, palliative radiotherapy, immunotherapy or chemotherapy. In 60% and 40% of patients SRT was delivered to brain and extracranial lesions, respectively. The assessment of the efficacy of SRT was based on a radiological imaging (Computed Tomography or Magnetic Resonance Imaging) and estimation of Local Control (LC) as well as Overall Survival (OS). Single fraction was used for 104 tumors and fractionated treatment for 47 tumors. The crude LC for evaluable lesions was 81%, stratified by tumor location: brain LC=94%, extracranial tumors LC=70% (p=0.049). The median OS was 9.4 months; 1-year and 2-year OS were 40% and 29%, respectively. The additional treatment did not lead to a better local response (p=0,543), but resulted in a benefit in OS (7 vs 13 months, p=0,01). A positive relationship between the biologically effective dose (BED) and local response was noted, but the BED was influenced by a tumor volume (R=-0,38; p<0,00001). The presence of multi-organ metastases reduced the OS rate (8.7 vs 19.1 months; p=0,01). The interval between the diagnosis of the metastasis and its treatment with SRT was inversely related to OS (P=0.0001). SRT results in a good local response, which is more beneficial for brain than extracranial lesions. The local efficacy of the SRT depends on the radiation dose. Multidisciplinary treatment and earlier application of SRT improves the prognosis of patients.