RESULTS

1. Comparative effectiveness of Partial versus Radical Nephrectomy in the treatment of patients with early-stage Kidney Cancer Hung-Jui Tan MD1, Edward C. Norton PhD2, Zaojun Ye MS1, Khaled S. Hafez MD1, John L. Gore MD, MS3, and David C. Miller MD, MPH1,2 1Department of Urology, University of Michigan; 2Center for Healthcare Outcomes and Policy, University of Michigan; 3Department of Urology, University of Washington INTRODUCTION RESULTS • Among patients with early-stage kidney cancer who were candidates for either surgery, treatment with partial rather than radical nephrectomy was associated with improved survival • This survival benefit appears to be most apparent among younger patients and those with comorbid conditions • By judiciously expanding the use of partial nephrectomy, especially among these patients, clinicians can optimize survival outcomes among patients seeking treatment for early-stage kidney cancer CONCLUSIONS METHODS Abstract ID: 1203329 • Context • Partial nephrectomy (PN) is the preferred treatment for many patients with early-stage kidney cancer, based on better preservation of renal function and potentially improved survival • Recent trial data has demonstrated equivalent, if not improved survival, for patients treated with radical nephrectomy (RN), at least during the early adoption of PN • Objective • To compare long-term survival after partial versus radical nephrectomy among a population-based patient cohort whose treatment reflects contemporary surgical practice Kaplan-Meier Survival Estimates (unadjusted) Estimated Survival Probabilities (model-derived) P=0.004 RN P=0.004 P=0.005 PN All-cause mortality, % P< 0.001 P< 0.001 Years Posttreatment p = .001 • Study Design and Patients • Retrospective cohort study of SEER-Medicare patients with clinical stage T1a kidney cancer treated with PN or RN from 1992 – 2007 • Two-stage residual inclusion model using an instrumental variable approach to estimate the treatment effect of partial nephrectomy on long-term survival (overall and kidney cancer specific) Kidney cancer mortality, % Time Posttreatment P< 0.001 RN Number Needed to Treat PN Years Posttreatment • Instrumental Variable • Induces variation in treatment with no direct effect on outcome • Generates pseudo-randomization to balance both measured and unmeasured confounders, thereby allowing estimation of the treatment effect for the “marginal patient” • Differential Distance = distance to surgeonPN – distance to surgeonRN P< 0.001 Marginal Patient Miles