For patients with completely endophytic kidney tumors, robot-assisted partial nephrectomy (RAPN) by skilled surgeons leads to favorable outcomes similar to open partial nephrectomy (OPN), according to a new study.

“Robotic partial nephrectomy results match the open approach for small localized endophytic renal masses, while affording a minimally invasive approach and shorter hospital stay,” lead investigator Jihad Kaouk, MD, of Cleveland Clinic in Ohio, said in a news release.


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Since excising endophytic tumors is challenging, OPN has been preferred. These tumors are not easily identifiable on visual inspection of the capsular surface, and the depth of resection is not immediately apparent, which increases the technical difficulty of the surgery as well as complication risk, Dr Kaouk’s team explained in a paper published online ahead of print in BJU International.

Dr Kaouk and colleagues compared surgical, oncological, and functional outcomes of 87 RAPN and 56 OPN cases performed at a single center between 2011 and 2016. The groups had a similar mean age (58.3 and 61.1 years, respectively) and a similar racial composition, with white patients predominating (82.8% and 87.5%, respectively). Surgeon experience was high for both approaches, beyond the learning curve. For all RAPN, surgeons employed a transperitoneal route, a drop-in ultrasound probe, and selective use of intracorporeal renal parenchyma cooling. More patients with a solitary kidney underwent OPN.

The investigators found no significant differences in tumor size, grade, stage, subtype, and margin status by approach.

Endophytic tumors have been linked with prolonged ischemia and longer operative time. Although there was a trend toward longer warm ischemia time with RAPN, analyses revealed no significant differences in warm or cold ischemia time between procedures. Duration of surgery was similar between groups, possibly due to surgeon experience. Intraoperative and posteroperative complication rates also did not differ. RAPN patients did experience shorter hospital stays (median 3 vs 5 days), less blood loss (mean 175 vs 341 mL), and lower rates of intraoperative blood transfusion (0 vs 7.1%).

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In addition, neither local cancer recurrences nor distant metastases occurred within the median follow-up of 15.2 and 18.1 months in the RAPN and OPN groups, respectively. The researchers also found no difference in preservation of estimated glomerular filtration rate by procedure at these time points. The study may have been underpowered to detect some differences.

“Ultimately, outcomes for OPN and RAPN for endophytic tumours [sic] are excellent when performed at an experienced centre by experienced surgeons,” the investigators wrote. “Therefore, selection of surgery should depend on surgeon experience and comfort with either approach.”


1.    1. Kara O, Maurice MJ, Malkoc E, et al. Comparison of robot-assisted and open partial nephrectomy for completely endophytic renal tumours: a single centre experience. BJUI. doi: 10.1111/bju.13572.

2. Study examines different types of surgery for kidney cancer. Wiley. Aug 1, 2016. [press release]