BERKELEY, CA (UroToday.com) - In this prospectively-derived analysis, we evaluate the surgical results and morbidity of the tumor enucleation (TE) technique for the conservative management of renal cancer. Compared to our previously published single-centre experience, the present study provides a significantly more accurate methodology on the following aspects: it uses an internationally validated instrument as the modified Clavien classification to stratify the severity of complications; the study population is more accurately described with the expression of the tumor nephrometry; and the statistical analysis is more meticulous since it includes the evaluation of independent predictors of surgical complications in the multivariable analysis.
This study is not only an analysis of morbidity after nephron-sparing surgery, but also represents the first validation of a nephrometric instrument for the TE technique. Nephrometry is a collection of the characteristics of the tumor, examined in the preoperative imaging, which predict the technical difficulty of partial nephrectomy (PN), and therefore the rate of complications.
The nephrometric variables of kidney tumors include: the clinical diameter, the growth pattern (exophytic or endophitic), the proximity to the renal pedicle, the relationship of tumor with the urinary collecting system and the vessels of the renal sinus, and so on. Due to the difficulties of individually analyzing these aspects, in recent years several nephrometric classification systems have been proposed. These systems convert the single parameter into a numeric subscore, the subscores are then added together to make a total nephrometric score: the higher the score, the more technically-demanding the tumor excision.
The R.E.N.A.L. score, C-Index, and the PADUA score have been externally validated for PN. However, none have been validated for the TE technique, which differs from the PN in that it excides the tumor with no visible rim of healthy parenchyma around it, and the cleavage plane between tumor pseudocapsule and the healthy parenchyma is developed by blunt dissection. Over the last years this technique has received a wider consensus, being adopted in several centers as an alternative to standard PN, particularly to treat cortico-medullar renal tumors. Our results confirm the validity of PADUA score for TE, since it resulted an independent predictor of postoperative surgical complications, as it has been shown previously for PN. By providing a validated nephrometric tool for TE, with this study we allow future comparative studies between TE and other techniques regarding oncological, surgical and functional results.
These studies require groups of patients as homogeneous as possible for all preoperative variables, including tumor nephrometry. We consider particularly advisable a comparison between TE and PN with respect to morbidity, as it is our belief that TE is technically easier, faster to perform, and that it can result in lower rates of postoperative complications in comparison to PN.
The theoretical rationale is that TE involves a minimal deepening of the excision in the parenchyma, reducing the accidental damage of major vessels and urinary calices, etiologic factor (in case of not corrective suture) of postoperative bleeding, and urinary fistula. Evidence to support this theoretical rationale comes from preliminary studies, like the present, showing a rate of postoperative complications that compares favorably with those reported in the literature after open PN. The present series may be seen to only represent the first step in shedding light on this controversial topic. Prospective comparative studies on surgical results and morbidity of PN and TE are needed in order to investigate this issue further.
Written by:
Andrea Minervini, Gianni Vittori, Giampaolo Siena and Marco Carini as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Department of Urology, University of Florence, Italy
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