Does the onset of bone metastasis in sunitinib-treated renal cell carcinoma patients impact the overall survival?

Abstract

To evaluate the impact of bone metastasis (BM) onset toward prognosis in metastatic renal cell carcinoma (mRCC) patients treated with sunitinib. mRCC patients with BM and sunitinib as first targeted therapy between May 2005 and December 2012 were retrospectively analyzed. Patients with synchronous (s) BM or metachronous (m) BM were compared with regard to treatment and outcome [time to clinical progression (TTcP), overall survival (OS), skeletal-related events (SRE)]. Descriptive statistics, Kaplan-Meier estimation of TTcP and OS, Cox regression analyses, and a landmark analysis were administered. BM was identified in 127 mRCC patients; thereof, 82 sunitinib-treated patients were analyzed [sBM n=57 (69.5%), mBM n=25 (30.5%)]. Higher tumor grading (p=0.029), male predominance (p=0.02), and less second-line therapy (p=0.001) were detected in sBM compared to mBM. SRE remained similar between subgroups (p=0.462). TTcP during sunitinib was similar [median sBM 8.1 (95% CI 3.9-12.3) vs. mBM 8.7 (95% CI 2.7-14.8) months, p=0.903]. OS remained significantly inferior in sBM patients compared to mBM [median sBM 21.1 (95% CI 16-26.2) months vs. mBM 38.5 (95% CI 15-62) months, p=0.001], which was confirmed by landmark analyses at 1.5, 3, 6, 9, and 12months. However, OS after occurrence of BM was similar in both groups [median sBM 24.2 (95% CI 17.3-31.1) months vs. mBM 17.2 (95% CI 8.4-26) months, p=0.519]. mBM is associated with an improved OS compared to sBM in mRCC with sunitinib treatment, despite similar efficacy of sunitinib treatment in both groups of patients.