Overall survival after stereotactic radiotherapy or surgical metastasectomy in oligometastatic renal cell carcinoma patients treated at two Swedish centres 2005-2014.

Background And Purpose: Investigate effects of stereotactic radiotherapy (SRT) or surgical metastasectomy (SM) on overall survival (OS) in metastatic renal cell carcinoma (mRCC) in the era of targeted agents (TA).

Material And Methods: mRCC patients (n = 117) treated with SRT (n = 57), SM (n = 30) or both modalities sequentially (n = 30) at two oncological centres in Sweden in 2005-2014 were retrospectively included. Median follow-up (mFU) was 63 months.

Results: A majority had clear cell histology, 1-3 metastases, and ECOG performance status of 0 or 1. Two thirds had intermediate or poor risk and 44% synchronous metastases. 65% received TA. SRT patients were more likely to have adverse risk profiles. Median OS was 51 months without significant differences between SRT and SM. ECOG 1 vs 0 (HR 2.9; CI 1.6-5.2; p < 0.001), intracranial targets (HR 1.8; CI 1.1-3.2; p = 0.03) and watchful waiting >18 months prior to treatment (HR 0.3; CI 0.2-0.6; p = 0.001) were independently associated with OS. 15% of curatively treated patients (n = 60) were relapse-free with mFU of 87 months.

Conclusions: OS after SRT was comparable to SM and longer than expected considering patients with adverse risk profiles were common. Fit patients with non-brain metastases treated after an initial period of watchful waiting had the best prognosis.