Image-guided percutaneous ablative treatments for renal cell carcinoma

Abstract

In recent decades, percutaneous ablation procedures have evolved into a recognized treatment option for renal cell carcinoma (RCC). Thermal ablation techniques, including radiofrequency ablation (RFA), microwave ablation (MWA), and cryoablation (CA) are now incorporated in most treatment guidelines as a viable alternative, and in some cases, deemed equivalent to nephron-sparing surgery (NSS) or other surgical methods, especially for small renal masses (SRM) up to 4 cm. This review offers an overview of the most prevalent ablation techniques used to treat localized RCC. Additionally, it compares the oncological and clinical outcomes of these techniques with those of surgical options. Finally, it provides an assessment of the role that ablation treatment occupies in current guidelines. In conclusion, the use and incorporation of image-guided minimally invasive treatment options for RCC is on the rise. Existing data suggest that thermal ablation procedures (RFA, MWA, and CA) and partial nephrectomy yield comparable oncologic and clinical outcomes. Despite the data available, the recommendations for thermal ablations vary significantly across national and international guidelines. KEY POINTS: Question Despite growing evidence and integration in international guidelines, recommendations for ablative procedures in localized small renal cell cancer vary considerably. Findings Existing, mostly retrospective, data suggest that thermal ablation and partial nephrectomy yield comparable clinical results for small tumors. Clinical relevance Based on the current literature, thermal ablation of renal cell cancer up to 4 cm in size can be offered to patients as an alternative to surgery.

Keywords: Cryoablation; Microwave ablation; Partial nephrectomy; Radiofrequency Ablation; Renal cell carcinoma.

Fig. 1

A, B Shows the contrast-enhanced CT in the weeks before the ablation and the native sonogram of a 36-mm papillary RCC at the lower pole of the left kidney. C Shows the intraprocedural cone-beam CT during RFA with ablation for 12 min and hydrodissection. D Shows the CT as a control scan with good local tumor control

Fig. 2

Seventy-nine-year-old female patient who presented for a second opinion. Initially, the patient was offered a resection of the upper third of the kidney. A Pre-interventional axial MRI slice with a 12 mm exophytic lesion suspicious for RCC in the upper pole of the kidney. Due to its size and location, the patient was offered MWA and diagnostic puncture for histologic confirmation in one session in analgosedation (fentanyl and midazolam). B Planning scan in the prone position and arterial phase (lesion indicated by white arrowhead). C Peri-interventional fluoroscopy CT scan with the position of the MWA antenna in the center of the lesion (white arrowhead). D Postinterventional scan obtained directly after ablation, indicating sufficient coverage of the lesion by ablation. The white arrowhead is pointing at the post-ablation area. Histology confirmed the diagnosis of clear cell RCC

Fig. 3

Sixty-four-year-old patient with suspected RCC. A (axial), B (coronar) Lesion measuring approx. 2.2 cm in the middle third of the kidney (white arrowhead) with an exophytic portion and growth towards the hilus. As the bowel is also closed (white arrow), the decision was made to perform CA (in analgosedation) with hydrodissection of the bowel. C CT-fluoroscopy image after 2 min, at the beginning of the 1st freezing cycle. The cranial of two needles is in the middle of the lesion (white arrowhead), while the white arrow is pointing at the fluid collection. The bowel was easily mobilized using 22 G needles and NaCl. D, E Control scan obtained after 5 min, in the second freezing cycle. The white arrowheads point to the clearly visible ice ball, and the parallel needle positions and the geometric shape of the visible ice ball can be seen in the sagittal and coronal slice guides angled onto the needles. F Complete ablation in the control area scan after 6 months in the MRI (T1 contrast-enhanced fat sat sequence). The histologic specimen yielded the diagnosis of papillary RCC

Fig. 4

Eighty-eight-year-old female patient with a strongly arterially hypervascularized RCC measuring 6 cm (white arrowhead) and the duodenum as an adjacent risk structure (A). Since the patient was in good general health and declined anesthesia, a CA was chosen. Due to the significant arterial hypervascularization, the lesion was angiographically transarterially embolized the day before the ablation (with alcohol and lipiodol). B Final DSA (digital subtraction angiography) and a strong lipiodol deposition in the tumor (black asterisk), while the kidney is well perfused. C Shows the control scan after 5 min, in the first freeze cycle. The strong lipiodol deposition in the tumor impairs visualization of the ice ball and the seven needles positioned for treatment. To the right of the tumor, there is a small 22 G needle for hydrodissection. D Intraprocedural image obtained during the freeze cycle. The patient underwent the procedure without significant pain and remained hemodynamically stable. E Control MRI was performed after 3 months, demonstrating complete devascularization of the lesion (white asterisk). F Scar formation 8 months after the ablation (white asterisk). Histology of the sample taken at the beginning of the intervention confirmed the diagnosis of clear cell RCC

Fig. 5

Seventy-one-year-old patient with a histologically confirmed clear cell RCC after prior treatment by transarterial embolization the day before the ablation. A The 4.1 cm lesion is located in the central anterior third of the kidney (white asterisk). The patient was referred for CT-guided HDR brachytherapy in analgosedation. B Intraprocedural control scan and one of three brachytherapy catheters within the lesion (white arrowhead). C Radiation plan. The blue line encircles the complete tumor volume with the surrounding red line indicating the 20 Gy isodose line. D Control MRI scan obtained after 6 months, demonstrating complete ablation with local tumor control