For Partial Nephrectomy Outcomes, Robot Bests Laparoscopy

Nick Mulcahy

October 20, 2016

In the treatment of small renal masses, robotic partial nephrectomy (RPN) has a superior morbidity profile compared with laparoscopic partial nephrectomy (LPN), according to an updated meta-analysis of related studies.

The results are the "strongest available evidence" regarding perioperative outcomes because no completed or ongoing randomized trials have compared the two approaches, say the authors, led by Jeffrey J. Leow, MD, a urology resident at the Tan Tock Seng Hospital in Singapore and researcher at Harvard Medical School in Boston, Massachusetts.

The new study is published in the November edition of the Journal of Urology.

Partial nephrectomy, in forms such as RPN and LPN, is the gold standard treatment option for clinical T1 renal masses, according to the authors.

However, surgical practice has already moved in the direction of the robotic approach for these masses, say Josh Halpern, MD, and Jim Hu, MD, MPH, urologists from the Weill Cornell Medical College in New York City, in an accompanying editorial.

"National practice patterns reveal that laparoscopic renal surgery has given way to the robotic approach likely, in part, due to the shorter learning curve for RPN and the inadequacy of laparoscopic training during residency," they observe.

Still, "surgeon experience remains paramount, regardless of operative approach," they add, while also declaring that "the diffusion of RPN and its superior outcomes may render LPN increasingly rare in the near future."

The study authors echo these comments and explain that the changes in kidney surgery follow those seen in prostate cancer. "The rapid adoption of robot-assisted radical prostatectomy has increased urologists' experience and familiarity with pelvic robotic surgery," they write.

Nevertheless, with regard to outcomes, the superiority of RPN vs LPN "is still a controversial issue," they also say, noting that other meta-analyses have had "mixed results."

Importantly, the recent publication of eight new studies (as late as 2015) necessitated "an updated and accurate meta-analysis," the authors summarize.

In their new meta-analysis, the investigators report multiple advantages with RPN, including shorter warm ischemia time, decreased likelihood of conversion to open surgery, and fewer positive margins and complications.

The team reported these outcomes after performing a literature search through December 2015 that totaled 4919 patients and 25 studies (which all compared RPN and LPN) and then executing a meta-analysis to evaluate safety, effectiveness, and functional outcomes.

The two groups did not significantly differ in terms of age, sex, laterality, and final malignant pathology.

However, patients treated with RPN had larger tumors (weighted mean difference [WMD], 0.17 cm; P = .001), higher mean nephrometry scores (WMD, 0.59; P = .002), and a decreased likelihood of conversion to laparoscopic/open surgery compared with patients undergoing LPN (relative risk [RR], 0.36; P < .001).

Patients treated with RPN also had, compared with those treated with LPN, a decreased likelihood of any complications (Clavien 1 or greater) (RR, 0.84; P = .007) and major complications (Clavien 3 or greater) (RR, 0.71; P = .023), positive margins (RR, 0.53; P < .001), and shorter warm ischemia time by 4.3 minutes (P < .001).

Both approaches had similar operative times (WMD, –12.2 minutes; P = .34), estimated blood loss (WMD, –24.6 mL; P = .15), and postoperative change in estimated glomerular filtration rate.

The new study does not report long-term oncologic outcomes, including overall survival, because of the short follow-up time.

Of the results, the authors highlighted the fact that the nephrometry score, which is a measure of tumor complexity, was higher overall in the RPN group, which nonetheless had superior outcomes overall. This is the first meta-analysis to consider tumor complexity and compare nephrometry scores in both groups, the authors say.

Previous meta-analyses comparing the perioperative outcomes of RPN and LPN had shown no differences in length of hospital stay, estimated blood loss, operative times, and complication rates, but these studies had small numbers, assert the meta-analysis authors.

The new meta-analysis more than doubled the previous study (Eur Urol. 2015;67:891-901) in terms of patient numbers.

The authors also discuss why RPN may be superior to LPN mechanistically.

The "main advantage" of robot-assisted surgery is "instrument dexterity, allowing the surgeon to perform the complex tasks of excising renal tumors and reconstructing the collecting system and the cortex, while working within the constraints of warm ischemia," they write.

In addition, the authors say that "while laparoscopic surgery inherently shares the same advantages of shorter hospital stay, reduced pain, quicker return to daily activities and better cosmesis compared to open surgery, the limited range of motion from laparoscopic instruments makes PN [partial nephrectomy] challenging."

No direct or indirect commercial incentive was associated with the study.

J Urol. 2016;196:1371-1377. Article full text, Editorial

Follow Medscape senior journalist Nick Mulcahy on Twitter: @MulcahyNick

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