The growing number of diagnostic procedures led to an increase of the incidence of early stage renal cell carcinomas (T1a/b). Nowadays, 50% of renal cell carcinomas are diagnosed incidentally and in 80% of the cases they are diagnosed in stage T1 without metastatic spread . In the last decade, a trend away from radical open resection towards nephron-sparing approaches has been observed. Image-guided percutaneous radiofrequency ablation (RFA) is an important minimally-invasive nephron-sparing treatment option for early stage renal tumors.
In clinical practice, computed tomography (CT) is the most commonly used technique of image guidance for percutaneous RFA. The technical success rates of percutaneous image-guided RFA are high with a primary technical success rate (defined as treatment success after one single RFA) between 69% and 100% and a secondary technical success rate (defined as treatment success after 2 or more RFAs) ranging between 90% and 100% . Major complications include bleeding, damage to the urinary system, nerve damage (especially intercostal nerves and genitofemoral nerve) and pneumothorax are in skilled hands generally rare, they occur with a frequency of 0-14% . In the majority of the cases the renal function is preserved, a relevant deterioration of renal function is very rare [4,5]. The 5-year local recurrence-free survival rates, metastasis-free survival rates, cancer-specific survival rates, and overall survival rates are 88–93%, 95–100%, 98–100%, and 58–85%, respectively [5,6].
Percutaneous image-guided RFA is already considered as the best treatment option for the treatment of T1 renal cell carcinomas in patients with significant co-morbidities, in patients with solitary kidney or von Hippel-Lindau disease. Various meta-analyses demonstrate that in case of adequate tumor and patient selection RFA shows oncologic results comparable with surgical resection. Overall survival is reported as being slightly higher for patients undergoing surgery. However, in this context it should be taken into account that the comorbidity of patients selected for RFA is often higher than for surgical candidates. Already well accepted indications for RFA are T1 renal tumors in patients with advanced age, significant co-morbidities, reduced renal function, single kidney, and refusal of surgery.
Low complication rates, preservation of the renal function, the opportunity of repeated treatment, low costs and short hospital stays are the advantages of image-guided percutaneous thermal ablation versus surgery.
Predictors for treatment success include tumor size smaller than or equal to 4 cm, peripheral tumor location as well as advanced operator experience. Transarterial embolization prior to RFA is an option to ensure safe and effective treatment of renal tumors exceeding 4 cm (T1b). For follow-up, contrast-enhanced magnetic resonance imaging should be performed in defined intervals. To further evaluate the efficacy of RFA in the treatment of renal cell carcinomas, randomized controlled clinical long-term follow-up studies are indicated.
Dominik Vollherbst1, Philippe L Pereira1 and Christof M Sommer2,3
1 Clinic for Radiology, Minimally-invasive Therapies and Nuclear Medicine, SLK Kliniken Heilbronn GmbH, Heilbronn, Germany.
2 Clinic for Diagnostic and Interventional Radiology, University Hospital Heidelberg, Heidelberg, Germany.
3 Clinic for Diagnostic and Interventional Radiology, Klinikum Stuttgart, Stuttgart, Germany.
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