EUROPEAN UROLOGY 71 (2017) 118–119
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Platinum Priority – Editorial Referring to the article published on pp. 111–117 of this issue
Cryoablation for cT1b Renal Tumors? Yet To Be Determined Firas G. Petros, Surena F. Matin * Department of Urology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
Cryoablation (CA) has emerged as a thermal ablative alternative to nephron-sparing surgery predominately for high-risk patients with a clinical T1a renal mass suspected to be renal cell carcinoma (RCC) or those refusing surgery [1,2]. In this issue of European Urology, Caputo and colleagues [3] report on a matched comparative analysis between CA and robot-assisted partial nephrectomy (PN) for clinical T1b renal tumors. In brief, this retrospective study compared 31 cT1b renal tumors treated with either laparoscopic or percutaneous CA to 31 PN patients matched 1:1 for some baseline parameters. After matching for age, gender, tumor size, RENAL nephrometry score, body mass index, Charlson comorbidity index, American Society of Anesthesiologists score, preoperative serum creatinine, preoperative estimated glomerular filtration rate, and solitary kidney, there was no significant difference between the CA and PN groups in these baseline variables. In a shortterm follow-up with survival analyses being limited to those diagnosed with RCC (further limiting the subsets to 22 and 28 patients in CA and PN groups, respectively), the authors found a higher but not significantly different postoperative complication rate for the PN group, a significantly higher local recurrence rate for the CA group, and similar overall and cancer-specific survival. They concluded that patients treated with CA for cT1b renal tumors had a significantly higher rate of local cancer recurrence at 1 yr compared to those treated with PN. There is no level 1 evidence reported on the oncologic and functional outcomes of CA in comparison to PN. Therefore, evidence is drawn from retrospective studies and meta-analyses with the inherent limitations of selection bias, which in these cases can be quite significant yet unmeasured. The choice of treatment modality has been left to the discretion of the treating physician and the ensuing
discussion with the patient. However, patient age, comorbidity, and tumor size and location seem to be the most influential factors driving the treatment decision between intervention and surveillance of renal masses [4], and it is likely that the comfort level of the urologist with the treatment modality is also a factor. Regarding the selection of CA technique, tumors managed by laparoscopic CA are more often multiple, anterior, and/or upper pole renal tumors. In contrast, percutaneous CA is favored over radiofrequency ablation or laparoscopic CA for larger, central, or endophytic posterior tumors and those with higher RENAL nephrometry score [5]. The American Urological Association guidelines suggest these ablative techniques for T1b renal masses as suboptimal oncologic strategies owing to a higher risk of local recurrence. Some authors have challenged this finding, with several publications showing similar residual tumor rates between the two approaches [6] and good disease control in short-term follow-up after CA [7]. Over the last decade, the modality has shifted from laparoscopic to percutaneous CA given its less invasive nature and lower cost [8] with reportedly equivalent outcomes [5,9]. The study by Caputo et al [3] included a significant historic cohort of laparoscopic CA (n = 25, 81%) without description of their distinct demographic data and tumor location. Details of adjunctive procedures that may reduce complication rates such as hydrodisplacement of the bowel (for percutaneous cases), angioembolization, and ureteral stent placement were not mentioned in this study. It is also worth mentioning that the definition of local recurrence in this report was not consistent with the published definition [1,7,9]. The current study considered a contrast-enhancing lesion in the ablation zone identified at 3-mo imaging as incomplete treatment or a post-treatment
DOI of original article: http://dx.doi.org/10.1016/j.eururo.2016.08.039. * Corresponding author. The University of Texas MD Anderson Cancer Center, Unit 1373, 1515 Holcombe Boulevard, Houston, TX 77030, USA. Tel. +1 713 7923250; Fax: +1 713 7944824. E-mail address:
[email protected] (S.F. Matin). http://dx.doi.org/10.1016/j.eururo.2016.09.004 0302-2838/# 2016 European Association of Urology. Published by Elsevier B.V. All rights reserved.
EUROPEAN UROLOGY 71 (2017) 118–119
change rather than a true recurrence, which may have impacted survival curves. Short-term and inconsistent follow-up in this study that was not included with matched baseline variables could further undermine a fair balance between CA and PN groups and limit a meaningful comparison with regard to recurrence between these two groups. Subsequently, survival curves were similar between the groups. The discrepancy in the follow-up between the groups of this study also factored into the higher postoperative complication rate noted in PN patients compared to the recent lower rates of complications reported in robot-assisted PN, even for complex tumors, with a recent study including patients from the same institution [10]. The most common reported complication for T1b tumors treated with CA is bleeding requiring blood transfusion [7]. The types of complications in the present study were not mentioned. When such data are presented to some patients, a deceiving argument could be made for CA as an approach with fewer complications and yet similar survival curves to PN. With a lack of randomized studies to analyze the outcomes of CA in comparison to PN, comparative observational studies of a large sample size with homogeneously treated patients are needed to minimize differences in baseline variables between the arms. Long-term and consistent follow-up across the groups is essential for survival comparison to be conclusive. Putting all of this together, the presented available data was not designed to answer the question raised by the authors, since methods represent unaccounted biases, despite very laudable efforts by the authors in matching the two different groups, and short follow-up. While our own sentiments reflect the concluding spirit of the study, questioning the role of CA for cT1b RCC, the fact is that the evidence is still missing.
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The potential advantage or disadvantage of CA for cT1b renal tumors is yet to be determined. Conflicts of interest: The authors have nothing to disclose.
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