Early-Stage Renal Cell Carcinoma Locoregional Therapies: Current Approaches and Future Directions

Abstract

Renal cell carcinoma (RCC) is the most common primary renal malignancy. Prevalence of RCC in developed countries has slowly increased. Although partial or total nephrectomy has been the first-line treatment for early-stage RCC, improved or similar safety and treatment outcomes with locoregional therapies have challenged this paradigm. In this review, we explore locoregional techniques for early-stage RCC, including radiofrequency ablation, cryoablation, and microwave ablation with a focus on procedural technique, patient selection, and safety/treatment outcomes. Furthermore, we discuss future advances and novel techniques, including radiomics, combination therapy, high-intensity focused ultrasound, and catheter-directed techniques.

Keywords: Renal cell carcinoma; SIRT; ablation; high-intensity focused ultrasound; locoregional therapy; radiomics.

Figure 1.

RFA for RCC. Images show prone, cross-sectional imaging of a 66-year-old man with biopsy-proven RCC. (A) Preoperative contrast-enhanced CT shows an enhancing right interpolar lesion, measuring up to 2.4 cm. (B) 6 months pre-treatment non-contrast-enhanced CT redemonstrates this lesion. (C) The first RFA probe is inserted within the superior portion of the lesion. Ablation was performed at 65 W for 8 minutes at this superior probe. (D) The second ablation probe is inserted at the inferior margin of the lesion, where ablation was performed at 65 W for 8 minutes. The more superior probe is partial visualized. (E) Post-procedural contrast-enhanced arterial (shown) and venous phase (not shown) images were obtained, revealing no perfusion to the ablated right interpolar renal mass. (F) It is a contrast-enhanced CT obtained 3 months after ablation which does not show enhancement at the post-treatment bed to suggest viable lesion as compared with the initial contrast-enhanced CT in panel (A).

Figure 2.

MWA for RCC. Images show prone, cross-sectional imaging of a 58-year-old man with biopsy-proven RCC. (A) Contrast-enhanced CT shows the initial finding of an enhancing posterior exophytic right interpolar lesion. (B) Post-contrast fat-suppressed T1-weighted MRI 6 months after the initial CT redemonstrates the enhancing lesion, measuring up to 1.7 cm. (C) 3 months later, pre-treatment non-contrast-enhanced CT shows the posterior exophytic lesion. (D) It shows real-time ultrasound guided placement of the MWA antenna probe within the posterior right interpolar renal lesion while monitoring for gas bubble formation. (E) Intraprocedural CT was performed after the first ablation to re-confirm probe placement. (F) is a contrast-enhanced CT obtained 1 year after ablation which does not show enhancement at the post-treatment bed to suggest viable lesion as compared with the initial contrast-enhanced CT in (A).

Figure 3.

Cryoablation for RCC. Images show prone, cross-sectional imaging of a 62-year-old man with biopsy-proven RCC. (A) Pre-treatment non-contrast CT shows left renal posterior exophytic tumor. (B) It shows 2 cryoprobes with a smaller, intervening hydrodissection probe inserted via a posterior approach. Saline hydrodissection was performed prior to cryoablation to provide adequate space for ablation and reduce risk of injury to surrounding posterior abdominal wall/paraspinal musculature. (C) It shows the ice ball formation. (D) It is a post-contrast fat-suppressed T1-weighted MRI obtained 6 months after ablation demonstrating devascularized tumor bed without residual or recurrent tumor.

Figure 4.

Proposed algorithm for locoregional therapy in RCC. *Implies that for patients with T1a tumors and who are good surgical candidates either locoregional therapy or PN is a viable option after multidisciplinary discussion with oncology, urology, and interventional radiology, and patient preferences.