Abstract: PD04-11
Sources of Funding: none

Introduction

Cytoreductive nephrectomy (CN) remains a mainstay in the treatment of metastatic renal cell carcinoma (mRCC). Prior literature has shown around 2/3rds of patients do not receive timely systemic therapy (ST) after CN, however there is limited understanding of how a delay affects progression and survival. Our aim was to identify whether a delay of the initiation of ST was associated with worse overall survival as well as to further characterize the reasons for a delay.

Methods

From an institutional database of 2,906 patients surgically treated for renal masses between 2005 and 2016, we identified 70 patients who underwent CN for mRCC and who were initiated on ST in the adjuvant setting. Cox regression analysis was used to evaluate whether delays in systemic therapy > 3 months and > 6 months were predictive of worse overall survival.

Results

Of the 70 patients, the majority had a favorable ECOG performance status (90% ECOG 0-1, 10% ECOG 2-3) while only 3 patients had brain metastasis at time of CN. Median age at diagnosis was 60 years. Our cohort had a 2-year overall survival of 60.8% from diagnosis and 49.4% after initiation of ST with a median follow-up of 27.1 months. Median time to ST after CN was 3 months (IQR 1.53-6.77). 94.2% of patients received targeted therapy while the remainder were treated with IL-2. Delays in initiating ST after CN were not associated with worse overall survival > 3 months after CN (HR = 0.64, p= 0.387, 95% CI 0.24-1.75) and from 3 to <6 months (HR = 0.5, p = 0.208, 95% CI 0.17-1.47). Interestingly, delays in ST > 6 months were associated with improved survival (HR = 0.19, p=0.017, 95% CI 0.74-0.017). Of the patients who experienced unintended delays, 42.3% were awaiting a clinical trial, 30.8% experienced delayed ST due to patient preference or poor follow-up, and 19.2% had a complication from surgical therapy.

Conclusions

A delay in the initiation of ST in patients with mRCC after CN did not appear to be associated with worse overall survival. The improved survival in patients who initiated ST > 6 months and trend towards improved survival at > 3 months after CN is likely related to an immortal time bias. Ongoing randomized controlled trials may provide more evidence regarding the optimal timing of ST after CN and the clinical implications of a delay in ST.

Funding

none