Partial nephrectomy: Viable in larger cortical tumors

Chicago-For appropriately selected patients with renal cortical tumors measuring up to 7 cm, partial nephrectomy (PN) appears to be a reasonable option that does not compromise overall or cancer-specific survival, according to the results of a retrospective analysis presented at the 2009 AUA annual meeting.

The study was a collaborative project pooling data from 1,159 patients with sporadic, unilateral, solitary, localized, 4- to 7-cm renal masseswho underwent PN or radical nephrectomy (RN) at Memorial Sloan-Kettering Cancer Center, New York, or the Mayo Clinic, Rochester, MN, between 1989 and 2006. Patients were excluded if they had a renal vein thrombus or evidence of T4 disease.

Analyses controlling for differences in clinicopathologic features between groups showed no statistically significant difference in overall survival between the PN and RN groups. An analysis of cancer-specific survival based on a subgroup of 943 patients with renal cell carcinoma for whom the cause of death could be determined showed RN patients had an approximately twofold higher risk of dying from their malignancy compared with the PN group.

"Partial nephrectomy has benefits for preserving kidney function and diminishing the likelihood of chronic kidney disease, along with the associated risk of cardiovascular morbidity and mortality. However, according to national databases, it is widely underutilized in the U.S. and abroad. Hopefully, the information from our study will encourage physicians and patients to consider partial nephrectomy for renal masses that are amenable to this approach."

Recent single-institution studies from the Mayo Clinic and Memorial Sloan-Kettering reported that in patients with small renal tumors (≤4 cm), RN was associated with decreased overall survival compared with PN. Unaware of any studies investigating outcomes of these surgical approaches in patients with larger tumors, the researchers were motivated to undertake this pooled analysis.

"Routine partial nephrectomy was first utilized in the 1980s, primarily in patients with solitary kidneys, and started to gain popularity in the 1990s, but is still in a state of evolution for patients with larger renal masses. Therefore, in order to have sufficient power to investigate whether use of partial nephrectomy impacts overall and cancer-specific survival, it was necessary to combine the databases from our two institutions," Dr. Thompson said.

Clinicopathologic differences

There were 286 patients in the PN group and 873 patients who underwent RN. Not surprisingly, the two groups showed significant differences in clinicopathologic features. Patients who underwent PN were more likely than patients in the RN group to have a solitary kidney (p<.001), diabetes (p=.08), or chronic kidney disease (p<.001), whereas the RN patients were significantly older and included a significantly higher proportion of females than the PN group; however, there was no difference in Charlson comorbidity index.

"Our study is subject to the biases inherent in a retrospective analysis, including surgeon selection bias in choosing patients for radical versus partial nephrectomy," Dr. Thompson said. "While our statistical analyses controlled for some of these differences, it is likely that patients selected for PN harbored tumors that were more exophytic, a feature that may have accounted for the improvement in cancer-specific survival for PN patients. Nevertheless, we believe the results support the use of PN whenever technically feasible for patients with renal cortical tumors up to 7 cm in size."