Enucleation for RCC yields multiple benefits

In patients undergoing robotic partial nephrectomy for renal cell carcinoma, renal tumor enucleation maximally preserves normal renal parenchyma and provides better surgical precision compared to the standard technique, and it appears to do so without compromising oncologic outcomes, reported Gopal N. Gupta, MD, at the AUA annual meeting in San Diego. 

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Dr. Gupta“Partial nephrectomy has gained favor for the surgical treatment of renal masses less than 7 cm because compared with radical nephrectomy, it maximally preserves normal renal parenchyma, thereby optimizing renal function and potentially overall survival,” said Dr. Gupta, of Loyola University Medical Center, Maywood, IL.

“Now, using a validated construct, we have demonstrated for the first time that when using a minimally invasive technique that further benefits patients, tumor enucleation is maximally parenchymal preserving and more precise than standard partial nephrectomy. In addition, our experience indicates tumor enucleation is safe from an oncologic perspective in the short term.”

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A retrospective study by Dr. Gupta and co-authors included 57 patients who underwent tumor enucleation and 53 patients who had standard partial nephrectomy. All of the patients had undergone computed tomography or magnetic resonance imaging preoperatively within 2 months before surgery and 4 to 12 months after surgery. They also had estimated glomerular filtration rate data from the same pre- and postoperative time frames.

Next: The authors' findings

The two surgical groups were well matched for median age, body mass index, and tumor size, although the tumor enucleation group had more high-complexity tumors than the standard partial nephrectomy group (RENAL score, 40.4% vs. 18.9%).

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Percent parenchymal mass preserved in the operated kidney was assessed with a previously published 3-D imaging-based method developed by Dr. Gupta and colleagues, and the median value was significantly greater with tumor enucleation versus standard partial nephrectomy: 96% (interquartile range, 89.6%-100.0%) versus 89% (IQR, 83.3%-96.3%) (p=.003).

Surgical precision was analyzed using a volumetric computerized tomography technique developed by co-author Steven C. Campbell, MD, at Cleveland Clinic. Defined as the actual postoperative parenchymal volume/predicted parenchymal volume (presuming loss of a 5-mm rim of normal parenchyma associated with tumor excision and reconstruction), median surgical precision was also significantly better in patients who underwent tumor enucleation compared with the standard partial nephrectomy group: 101% (IQR, 95.5%-105.1%) versus 94% (IQR, 88.3%-100.0%) (p<.001).

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Other findings showed that function of the operated kidney was better preserved after tumor enucleation versus standard partial nephrectomy (96% vs. 93%), although the difference between groups did not achieve statistical significance.

Next: No positive margins in either group

Histologic assessments showed there were no positive margins in either group, and the authors reported there were no cases of tumor recurrence during a median follow-up of 2 years.

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“Certainly, we would like to have additional follow-up to establish long-term oncologic efficacy, but the technique of tumor enucleation is nothing new. It has been used for years in open surgery and shown to provide good oncologic control,” Dr. Gupta said.

The authors also reported that the majority of tumor enucleation cases were completed with zero warm ischemia time.

“Tumor enucleation leverages the biology of these renal cancers. Using the plane between the peritumor pseudocapsule and the renal parenchyma as a guide for dissection, enucleation not only minimizes the removal of normal parenchyma, but it also minimizes warm ischemia time. In carefully selected patients, therefore, tumor enucleation is a win-win situation,” Dr. Gupta said.

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