Litmus test or destination systemic therapy? Trends in referral for surgery after initial systemic therapy in metastatic kidney cancer.

Abstract

502 Background: With nine new targeted and immunotherapeutic agents for metastatic kidney cancer (mRCC) since 2005, there is no randomized data supporting sequencing cytoreductive nephrectomy (CN) and newer systemic therapies (ST). Increased disease control with ST engenders concern that CN may shorten life or delay therapy. Thus, in all the best prognostic candidates, initial ST as a “litmus” test may be advocated prior to CN. We evaluated use of CN after initial ST, hypothesizing receipt of deferred CN to be associated with increased survival time, markers of increased performance status, less rapid disease, and socioeconomic status. Methods: The National Cancer Database was screened for adult patients with biopsy-proven mRCC treated with initial systemic therapy between 2006-2013. Covariates included demographic, oncologic, hospital-level, and geographic variables. Unadjusted and multivariable logistic regression was performed, identifying factors associated with CN after initial ST. Results: Of 14,651 patients treated with initial ST for mRCC, 709 (4.8%, median OS 19 months, IQR 9-35) underwent delayed CN compared with 13,942 (95.2%, median OS 5 months, IQR 2-13) treated with ST alone. On multivariable analysis, survival ≥3 months was highly associated with receipt of CN (OR 10.6, 95% CI 5.5, 20.5). However, of 9,796 surviving ≥3 months, only 689 (7%) underwent CN. Factors associated with lower odds of CN included older age, greater comorbidity, higher clinical stage (T and N), and unfavorable metastatic sites (i.e., brain, bone, liver) with all p<0.001. Educational attainment was associated with receipt of CN, but hospital characteristics and travel burden were not. Conclusions: Effectiveness of CN in the modern mRCC era is uncertain. Initial ST is typically for those with poor prognosis. Yet, after an initial litmus test, re-evaluation of risk rarely leads to CN. Socioeconomic factors may affect CN decision-making, a potential disparity that merits further investigation.