When Partial Nephrectomy Is Unsuccessful: Understanding the Reasons for Conversion From Robotic Partial to Radical Nephrectomy at a Tertiary Referral Center - Expert Commentary

Partial nephrectomies are the standard of care with treatment of T1a or T1b tumors due to their better functional outcomes and decrease cardiovascular morbidity. However, with the increasing trend of using robotic partial nephrectomy (RPN) to treat more and more complex tumors, there is a greater risk of conversion to radical nephrectomy (RN). As there is little literature about analyzing the conversion rate and risks, these authors investigated the incidence of RPN to RN conversion and analyzed the preoperative factors that could possibly lead to a RN without having to convert. 

This study utilized 1,023 RPN cases performed at the Glickman Urological and Kidney Institute in Ohio. They standardized the tumor complexities using the R.E.N.A.L. scoring system and performed each case using the standard RPN technique with the grouping of the outcomes based on patient and tumor characteristics as well as the occurrence of RN conversion. To analyze their data, the authors used multivariable analysis with logistic regression to identify predictors of conversion.

Of the 1023 patients slated for a RPN, 32 were converted to RN intra-procedure. 71.9% of these were unintentional and another 71.9% were anticipated with the typical reason for conversion being tumor involvement of hilar structures. There were several complications among the patients who were converted but none were fatal. Commonly, the patients that required conversion were older and had a higher CCI such as having an increased prevalence of CKD and a lower preoperative eGFR. Additionally, the tumor size and complexity were also greater in those who underwent conversion with them being more likely to be in close proximity to the collecting system or renal sinus. Obviously, cases requiring conversion had longer operative times, but they also had a higher intra-operative transfusion rate as well, while the post-operative complication rate, in-patient length of stay, and the readmission rate did not significantly differ between converted and standard cases. 

One great strength of this article was the thoroughness of the researchers that allowed them to evaluate more factors than others previously have in literature. An example of this was how they viewed pre-operative notes to determine whether the surgeons expected to convert or not which enabled them to analyze which variables the surgeons saw that made them think they would have to convert and so then compare this to the independently verified variables that they discovered to see whether there was a correlation or not. This also caused them to evaluate whether they should actually perform RPN in those complicated cases, which would decrease the operating time and transfusion rate in their patients. However, in certain patients such as those with solitary kidneys or bilateral disease, the benefits of PN far outweigh the risks. For this study, I would have liked to see the authors analyze differences between men and women as well as men have a higher incidence rate for kidney cancer and I wonder whether they also have higher conversion rates as this would have been easily accessible through their database and just a simple calculation to show significance. Additionally, it seems the surgeons were not as experienced as they had a much higher conversion rate than other institutions that does not appear to be explained by the fact they are part of a tertiary clinic as well as how it seems that most surgeons were not confident in their ability to keep the surgeries as partials. The study did successfully illuminate the factors that typically led to conversion which were increased tumor size and complexity and poor preoperative renal function.

Written by: Zhamshid Okhunov, MD Department of Urology, University of California, Irvine Urology

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