Clinical outcomes of patients treated with local therapies with oligometastatic renal cell carcinoma (mRCC).

In a subset of patients with oligometastatic (mRCC), there may be a role for local therapy in an attempt to delay the need for systemic therapy. Techniques like stereotactic body radiotherapy (SBRT) have shown promise in achieving local control in RCC. We review our institutional experience of the use and outcomes for patients with mRCC treated with local therapies.

An IRB-approved retrospective analysis of the electronic medical record (including imaging) of mRCC patients treated at the Cleveland Clinic was carried out to identify those who received local therapies (such as SBRT, cryoablation, radiofrequency ablation (RFA), intensity-modulated radiation therapy (IMRT), and microwave ablation) in the treatment of non-CNS, non-bone oligometastatic disease. Variables analyzed included baseline patient, tumor and treatment characteristics, outcomes, and toxicities graded per CTCAEv4. Patients receiving local therapies to CNS lesions or bone or for palliation of symptoms were excluded.

From 2008-2017, a total of 14 patients met criteria for analysis. Median age was 64 years (range 50-76), 78.6% were men, all had clear cell RCC. Median follow-up from diagnosis of metastatic disease to last follow up was 39.5 months (range 1-136).

A total of 19 lesions were treated (84% lung, 11% liver, and 5% renal bed). Treatments were SBRT (74%), cryoablation (11%), IMRT (5%), RFA (5%), and microwave ablation (5%). Three patients (16%) had received one prior systemic therapy (sunitinib, IL-2, and sorafenib) and were treated with local therapy due to oligoprogression. Two patients received prior neo-adjuvant and adjuvant systemic therapy on clinical trials. One patient had prior metastasectomy. SBRT dose schedules ranges 30Gy in 1 fraction to 60 Gy in 3 fractions.

Treatment adverse events were limited (26% G1-3) including one patient with grade 3 pleural effusion post cyroablation, one patient with grade 2 pneumonitis post SBRT, and 3 patients with grade 1 fatigue post SBRT (all after treatment to lung lesions).

The median time from local therapy to systemic or local progression was 10 months (range 3-60). Seven patients (50%) progressed systemically at a median of 9 months after local therapy and one patient had local progression (at 60 months) in the liver re-treated successfully with microwave ablation. Nine patients (64%) have not required further systemic therapy. The median number of further systemic therapies used upon progression was one. Three patients died due to complications of their disease.

Local therapies are safe and feasible for visceral oligometastatic disease with the majority of patients demonstrating local control with minimal toxicity. Prospective studies are warranted to determine if local therapy in mRCC alters the natural history and/or can delay the need for systemic therapy.