Metastatic Tumor Burden Does Not Predict Overall Survival Following Cytoreductive Nephrectomy for Renal Cell Carcinoma: a Novel 3-Dimensional Volumetric Analysis.

OBJECTIVE: To compare 1-dimensional (1D) and 3-dimensional (3D) volume measurements and determine whether primary tumor (PT) burden is predictive of overall survival (OS) following cytoreductive nephrectomy (CN) for metastatic renal cell carcinoma (mRCC).

MATERIALS AND METHODS: Records and imaging studies of patients with mRCC treated with CN from 2006 to 2015 were included, with tumor volumes measured by a faculty radiologist blinded to clinical outcomes using Advantage Workstation Volume Share (Ver 4.6, GE, Waukesha, WI).

RESULTS: Complete PT and metastatic tumor volumes were measured for 67 patients. For 15 (22.3%) patients, 1D volume was within ±10% of the measured 3D volume. In 40 (59.7%) patients, the 1D calculated PT volume was >10% of the actual 3D volume. Fractional percentage of tumor volume (FPTV) removed during CN was calculated using the formula PT volume/(PT + met volume). FPTV was not associated with OS when analyzed as a continuous variable. Patients were divided into 2 groups based on previously published cut point of 90% FPTV. No differences between cohorts in age, gender, grade, subtype, number of metastatic sites, performance status, Memorial Sloan Kettering Cancer Center risk group, or International Metastatic Renal Cell Carcinoma Database Consortium risk group were identified. OS was not different between cohorts (P = .38).

CONCLUSION: 1D measurements of PT diameter frequently overestimate mRCC PT volume. In patients with mRCC selected for CN, the ratio of primary to metastatic tumor does not predict OS.