Benefit of Metastasectomy in Renal Cell Carcinoma: A Propensity Score Analysis.

Abstract

To quantify the magnitude of benefit of metastasectomy as compared to medical treatment alone in patients with metastatic renal cell carcinoma (mRCC). We therefore conducted a propensity score analysis of overall survival (OS) in 106 mRCC patients with metachronous metastasis, of whom 36 (34%) were treated with metastasectomy, and 70 (66%) with medical therapy alone. The most frequent metastasectomy procedures were lung resections (n=13) and craniotomies (n=6). Median time-to-progression after metastasectomy was 0.7 years (25th-75th percentile: 0.3-2.7). After a median follow-up of 6.2 years and 63 deaths, 5-year OS estimates were 41% and 22% in the metastasectomy and medical therapy group, respectively (log-rank P=.00007; Hazard ratio (HR)=0.38, 95%CI: 0.21-0.68). Patients undergoing metastasectomy had a significantly higher prevalence of favorable prognostic factors, such as fewer bilateral lung metastases and longer disease-free intervals between nephrectomy and metastasis diagnosis. After propensity score weighting for these differences and adjusting for immortal time bias, the favorable association between metastasectomy and OS became much weaker (HR=0.62, 95%CI: 0.39-1.00, P=.050). Propensity-score-weighted 5-year OS estimates were 24% and 20% in the metastasectomy and medical therapy group, respectively (log-rank P=.001). In exploratory analyses, the benefit of metastasectomy was confined to patients who achieved complete resection of all known metastases. Within the limitations of an observational study, these findings support the concept of metastasectomy being associated with an OS benefit in mRCC patients. Metastasectomies not achieving complete resection of all known lesions are likely without OS benefit.