Which future for percutaneous renal ablations?
Image-guided percutaneous renal ablations have been proposed since the early 2000s as a therapeutic alternative option to nephrectomy for the management of small renal tumors, mainly T1 (<7cm). Because of their minimally invasive but still experimental natures, these treatments were initially proposed in elderly patients (> 65 years of age), with co-morbidities, refusing surgery, having a single kidney or with family history (Van Hippel Lindau in particular) (1). Fifteen years after these promising debuts, it is legitimate to ask what will be the future of these techniques? To address this essential question, it is necessary to consider different facts. The first argument, essential from a clinical perspective, is whether the results of the ablations to date are up to expectations. The answer is definitively yes. The results now reported in the long term on a highly selected population at risks are very similar to those of surgery in terms of local control for comparable tumor sizes (more than 95% for tumors <4cm) with a low complication rate, decreasing to less than 4% over time with assimilation and optimization of the techniques (2,3). In addition to improving guidance and teaching, technical advances have been made by introducing different systems allowing to choose one technique over another depending on the location or size of the tumors. Following the rise of radiofrequency ablation, cryoablation improved the control of procedures by the direct visualization of the ice and allowed the reduction of renal fistula complications by protecting the urothelium for central tumors (4,5). More recently, microwave ablation appears to be valuable even if further evaluation is still necessary (6). The same applies to irreversible electroporation. The second point to consider is to identify all the means allowing to optimize practice and to reinforce the legitimacy of ablative treatments. Indeed, in parallel with the ablations' progress, the surgery also progressed prodigiously. Partial nephrectomy has become safer and less invasive. It is performed laparoscopically, under robotic control, with at best supra-selective clamping regularly allowing simple tumor enucleation. The effects on renal function are then undetectable, whereas this advantage was also defended after ablations (7). Ambulatory care has even become possible (8). As it is defended in interventional oncology, one of the simplest means to gain legitimacy in ablations is to adopt the methods of oncology but also to learn from the mistakes of the past (9). For instance, too many studies have investigated the feasibility of the ablations without recording the nature of the lesions treated, thus limiting their value as treatment or renal cancer. It is therefore essential to collect all the information related to these treatments. This involves the systematic realization of biopsies days before the ablation, except in case of major issues (eg anticoagulation), to be certain of the diagnosis and to allow standardized follow-up of the patient thereafter (10). It is likely, however, that imaging, especially performed by MRI, may help in the future to better select these patients (11). The collection of demographic and technical data is also indispensable in registers (eg via UroCCR database: http://uroccr.isped.u-bordeaux.fr/) and a reflection on the standardization of protocols, reports and follow-up should be carried out through the establishment of recommendations (12). All this justifies the need to meet patients in consultation, to follow recommendations and classifications developed in oncology or surgery (eg the RENAL nephrometry scoring system) while ensuring follow-up as any clinical specialty. Thirdly, there is a need to change practice to consider indications for treatment of a patient presenting a renal tumor according to the clinical context and all available therapeutic options. In addition to ablation and surgery, radiotherapy, active surveillance or therapeutic abstention may be offered to patients at multidisciplinary meetings. Knowledge of the clinical context and the nature of tumor after biopsy, but also using imaging, enables the patient to get the best therapeutic option by evaluating the benefits and risks of each technique. Our duty is to present objectively the advantages of ablations, which is to allow a minimally invasive curative treatment or renal tumors often under local anesthesia and sedation, and potentially in ambulatory. This may justify discussing the extension of indications to all renal tumors, malignant or benign, as recently proposed by the American Society of Clinical Oncology on the sole basis of the safe feasibility of the ablation (13). This will be more obvious if comparative multicenter prospective studies are conducted (14). It is also essential to obtain the reimbursement of these treatments or accommodate the patients within our radiology department in order to free us from economic constraints for the benefit of an increasing number of patients. In conclusion, although renal ablations are competing with other management options, their safety and effectiveness are no longer objectively to be demonstrated. However, it remains essential to continue their evaluation in order to incorporate them more widely as therapeutic options. Only the cooperation between the different specialties, involved at the same level in the therapeutic pathway of the patients and following the same methods in the evaluation of treatments, will ensure the future of percutaneous renal ablations (and interventional oncology). But it depends only on us.
References:
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