San Diego, CA USA (UroToday.com) In this session, the group from Fox Chase Cancer Center looked at overall survival differences between patients undergoing partial versus radical nephrectomy for Stage 1-2 renal cell carcinoma. Retrospective studies have purported improved overall survival (OS) for patients who undergo partial nephrectomy relative to radical nephrectomy.
However, these analyses are fraught with selection biases (i.e. generally speaking, patients selected for partial nephrectomy are healthier and would therefore be expected to have better OS). The best way to eliminate such selection biases is in the context of a randomized clinical trial. In fact, we have one of those in EORTC 30904 which paradoxically demonstrated an improved OS for radical nephrectomy over partial nephrectomy in patients with renal masses 5cm and less. This study suffered from methodological flaws such as failure to accrue. In addition, when only patients with pathologically confirmed renal cell carcinoma were considered, the differences in OS were no longer significant. Other RCTs have been proposed by Campbell and Miller, however, these were shot down over concerns about the potential for adequate enrollment.
We are left then with how to account for the problems of selection bias within the context of observational studies. Two common methods of doing this are through the use of propensity score based weighting and the use of instrumental variables. These studies have been done in the Medicare population for T1a renal masses and seem to demonstrate improved initial OS for patients undergoing partial nephrectomy, though these differences are tempered over time.
Dr. Ristau and colleagues analyzed the national cancer database and utilized propensity score based weighting in an attempt to account for selection biases. 179,846 renal cell carcinomas were stratified by size into T1a and T1b/2 tumors. Increased utilization of partial nephrectomy over time for both T1a and T1b/2 tumors was seen from 2003-2012. In the entire cohort, 54.6% and 15.8% of T1a and T1b/2 masses were treated with PN Adjusted 5-year overall survival in T1a and T1b/2 for partial and radical nephrectomy were 89% and 84.6% (T1a, p < 0.01) and 81.3% and 80.0% (T1b/2, p = 0.045). The HR in favor of partial nephrectomy for T1a and T1b/2 was 0.74 (95% CI 0.71-0.76, p < 0.001) and 0.90 (95% CI 0.85-0.96, p = 0.002), respectively. When stratified by length of time after surgery and by age group, the greatest benefit for partial nephrectomy was noted in young patients with small tumors. Overall survival benefits in patients with T1b/2 tumors are tempered in comparison. In patients older than 65 years with larger tumors, PN appears to offer little OS benefit relative to RN
The authors concluded that the decision to perform partial nephrectomy in older patients with larger tumors is not straightforward and should be made in the context of competing risks and with sound clinical judgement.
Presented By: Benjamin T. Ristau, MD