MILAN—Partial or radical nephrectomy is associated with a significant cancer-specific survival advantage over active surveillance for the management of localized kidney cancer among patients younger than 75 years, according to findings presented at the 28th annual congress of the European Association of Urology.

The protective effect of immediate surgery, however, needs to be weighed against the risk of death from other causes, said Maxine Sun, PhD, of the University of Montreal Health Center, the study’s lead investigator.

Using data from the Surveillance, Epidemiology and End Results (SEER)–Medicare linked database, Dr. Sun and her colleagues studied an observational cohort of 10,595 patients with clinically node-negative T1 renal cell carcinoma (RCC) treated with nephrectomy or non-surgical management (NSM) from 1988 to 2005. Compared with patients treated with NSM, those treated with partial nephrectomy (PN) or radical nephrectomy (RN) had a significant 55% and 42% decreased risk of cancer-specific mortality (CSM), Dr. Sun reported. In the subset of 6,443 patients with T1a RCC the reduction in CSM risk was 59% and 53% for PN and RN, respectively.

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The five- and eight-year CSM rates for the overall cohort were 10.2% and 11.7%, respectively, for NSM, 6.7% and 8.8% for RN, 3.1%, and 4.9% for PN. For patients with T1a RCC, the CSM rates were 7.4% and 8.5%, for NSM, 4.5% and 5.7% for RN, and 2.6% and 4.7% for PN.

Among patients aged 75 years and older, CSM did not differ significantly between patients who had nephrectomy or NSM.

“The current findings of this study show that it’s very important to adequately select surgical candidates, as our results show that some of these patients do not live long enough to benefit from surgery,” said Dr. Sun, who added that clinicians still face the dilemma of being unable to differentiate aggressive from non-aggressive tumors.

Furthermore, the results corroborate existing contemporary guidelines, which recommend active surveillance in patients with limited life expectancy, she said.

At the recent 2013 Genitourinary Cancers Symposium, William C. Huang, MD, and colleagues reported on a study showing that surveillance for renal masses smaller than 4 cm was associated with a significant 16% decreased risk of death from any cause but that cancer-specific survival did not differ by management approach. The study also found that surveillance was associated with a significantly lower risk of cardiovascular events over time.

Alexander Kutikov, MD, Associate Professor of Urologic Oncology at Temple University’s Fox Chase Cancer Center in Philadelphia, noted that “we must await publication of finalized manuscripts from each group to make meaningful comparisons between the two studies.”  He warned, however, that these data “must be interpreted with extreme caution because a ‘no treatment’ group in an administrative dataset such as SEER cannot be equated to cohorts on active surveillance in modern urologic practice.” This is underscored by the fact that more than 30% of patients in each study were on so-called “active surveillance.”

“This percentage is extremely high even for institutions that have a robust active surveillance protocol in place today, while the cohorts captured patients from earlier time periods, before active surveillance ever gained meaningful clinical traction,” Dr. Kutikov said. “Furthermore, although the Sun and Huang groups used sophisticated statistical manipulations such as instrumental variable analysis and propensity score methodology [respectively], it is virtually impossible to appropriately adjust for measured and unmeasured confounders in pre-selected heterogeneous cohorts, thus rendering conclusions from these analyses hypothesis-generating at best.”