Overall survival advantage with partial nephrectomy: A bias of observational data?

Abstract

the Urologic Diseases in America ProjectBACKGROUND: Partial nephrectomy (PN) and radical nephrectomy (RN) are standard treatments for a small renal mass. Retrospective studies suggest an overall survival (OS) advantage, however a randomized phase 3 trial suggests otherwise. The effects of both surgical modalities on OS were evaluated compared with controls. METHODS: A matched cohort study was performed using the Surveillance, Epidemiology, and End Results (SEER)-Medicare dataset. Individuals treated with PN or RN for localized renal cell carcinoma (RCC) measuring 4 cm were compared with 2 control groups (non-muscle-invasive bladder cancer (BCC) and noncancer controls (NCC). Using a greedy algorithm, RCC groups were matched with controls by demographics and comorbidities. OS for surgical groups and controls were compared. The cause of death was evaluated for cancer groups when differences in OS were noted. RESULTS: Patients undergoing PN and RN were matched with controls. All cancer groups had >95% 10-year cancer-specific survival (CSS). Median OS was similar between RN (9.05 years) and BCC (8.67 years; P 5.067) and NCC (8.77 years; P 5.49). Median OS was improved for PN (10.45 years) compared with BCC (8.75 years; P<.001) and NCC controls (8.76 years; P<.001). A multivariate Cox hazards model demonstrated that PN improved OS compared with NCC (hazard ratio, 1.257; P<.001) and BCC (hazard ratio, 1.364; P<.001). CONCLUSIONS: RN patients had similar OS compared with controls, suggesting that this treatment modality does not compromise survival. Patients undergoing PN had improved OS compared with controls, suggesting possible selection bias. The apparent survival advantage conferred by PN in SEER-Medicare case series is likely the result of selection bias involving unmeasured confounders.

Impact of histological subtype on outcomes of renal cell carcinoma patients

“…This is in line with previously published population-based analyses and it has been partially explained by the preservation of renal function with partial nephrectomy [5,[24][25][26]. However, this apparent superiority of partial nephrectomy has been challenged by the possibility of observational selection bias in these retrospective studies [27]; given the fact that patients referred for partial nephrectomy are more likely to be of earlier Tumor Node Metastasis (TNM) stage and/or more geographically favorable location compared to those referred for total nephrectomy and also given the fact that patients referred to ablative treatment are usually medically inoperable because of co-morbidities. Thus, plenty of confounding factors may hinder definite conclusions based solely on retrospective studies.…”

Long-Term Outcome of Nephron-Sparing Surgery Compared to Radical Nephrectomy for Renal Cell Carcinoma ≥4 cm - A Matched-Pair Single Institution Analysis

“…Showing identical survival rates, PN showed a better renal function preservation in their collective [11] . These survival rates are confirmed by recent studies on this topic [12][13][14] . Concerning renal function, other studies confirm that PN is associated with a better preservation of renal function [7,[13][14][15][16][17][18] .…”

Is overall survival not influenced by partial vs radical nephrectomy?

“…This indicates that the patients included in these nonrandomized studies were different from the start, meaning that those selected for PN were 'better' patients who obviously had less cardiovascular disease and therefore had better cardiovascular outcomes. Another study confirmed that both PN and RN impact on cardiovascular disease [7], whilst another meta-analysis showed no difference for cardiovascular outcomes [8]. Obviously patients with preoperative CKD will benefit from nephron-sparing surgery [9], as well as those who have concomitant conditions, e.g.…”