Ablative therapy for Renal masses
Thermal ablation utilizing cryoablation, radiofrequency ablation (RFA) and Microwave ablation (MWA), is a new, minimally invasive modality employed as an alternative to surgery in patients with renal mass, who are not fit for surgery.
Keypoints:
| Treatment options for Renal cell carcinoma | 1. Stage I (T1a and T1b) - Partial or less commonly radical nephrectomy and ablation therapy. 2. Stage II and III tumors - Radical nephrectomy 3. Stage IV tumors - Radical nephrectomy only as cytoreductive measure |
| Indications for Ablative therapy | 1. Solitary kidney, 2. Multiple synchronous RCC 3. Von Hippel Lindau disease, tuberous sclerosis, Birt-Hogg-Dubé syndrome - Bilateral disease 4. Familial RCC 5. Those with limited renal function (GFR 60ml/min/1.73m2) |
| Risk Factor | 1. Cigarette smoking, 2. Obesity and 3. Hypertension |
| Ideal Tumor Size | 1. Solid renal masses less than 4 cm (T1a) in a noncentral location. 2. ESMO guidelines - small cortical tumors (≤3 cm) not suitable for surgery (see indications) |
| Location based approach | 1. Anterior or anterolateral upper pole of the right kidney - transhepatic approach 2. Anterior or medial upper pole of the kidney - adrenal gland at risk for thermal injury (intraprocedural blood pressure fluctuations with potential risks related to hypertensive crisis). A α-receptor blockade for 7–10 days before, aggressive blood pressure monitoring and coordination with the anesthesia team. 3. Medial lower pole of the kidney - nerves (genitofemoral or lateral femoral cutaneous nerves ) along the anterior aspect of the psoas muscle at risk of thermal injury. Use of pneumo-dissection or hydro-dissection 4. Central tumor location - Cryoablation has provided better outcomes than RFA for the treatment of central renal tumors. Endophytic tumor shows increased local treatment failures. |
| Proximity to adjacent structures | 1. Bowel - Tumor is 1 cm or less from the bowel. - Try changing patient position (e.g., rolling the patient), pneumo-dissection or hydro-dissection. 2. Proximal Ureter - Renal tumor is 1 cm or less from the proximal ureter - Pyeloperfusion of ureter using external ureter stent or retrograde approach. - Internalization of the stent for approximately 2 months may be considered if there is significant concern that the ablation zone extended to involve the ureter |
| Most common ablative technique | Cryoablation (better control and easy visibility of ablation zone, especially in large tumors, for centrally located tumors - less risk of injury to pelvicalyceal system, Less heat sink effect )and RFA/MWA |
| Anesthesia | General anesthesia is preferred. |
| Cystic and predominantly cystic nodules | Probe might need to be moved to different locations within the cystic tumor to ablate the solid components. |
| Nephrometry scoring systems | 1. PADUA (Preoperative Aspects and Dimensions Used for an Anatomical Classification System) 2. R.E.N.A.L (Radius, Exophytic/endophytic, Nearness, Anterior/posterior, Location) 3. C-index (Centrality Index) |
| ABLATE algorithm | 1. A (Axial Tumor Diameter) 2. B (Bowel Proximity) 3. L (Location Within Kidney) 4. A (Adjacency to the Ureter) 5. T (Touching Renal Sinus Fat) 6. E (Endo/Exophytic) |
| Post-procedure | 1. Contrast CT/MR 4 weeks after procedure to look for any residual enhancement (> 15 HU). 2. Crescent-like band or ‘‘halo’’ is seen around the ablation zone and has been reported as an imaging marker of treatment success |
| Contraindications | 1. Uncorrectable coagulopathy 2. Sepsis 3. Extra renal disease or Endovascular invasion 4. Relative Contraindication- Adjacent vital organs such as the bowel cannot be adequately displaced |
| Complications | 1. Injury to ureter, ureteral strictures, ureteropelvic junction obstruction - pyeloperfusion during the procedure 2. Bowel perforation, reno-colic fistula, reno-duodenal fistula - use hydro dissection with 5% dextrose, CO2 3. Nerve injuries genitofemoral and ilioinguinal nerves, lesions near psoas muscle), 4. Injury to adrenal gland - acute hypertensive crisis or delayed adrenal insufficiency in patients with a prior contralateral adrenalectomy 5. Injury to muscles 6. Hematuria - after ablation of centrally located tumors |
Important research and publications:
| Publication / Research | Results | Author's Conclusion |
|---|---|---|
| Georgiades, Christos S, and Ron Rodriguez. “Efficacy and safety of percutaneous cryoablation for stage 1A/B renal cell carcinoma: results of a prospective, single-arm, 5-year study.” Cardiovascular and interventional radiology vol. 37,6 (2014): 1494-9. doi:10.1007/s00270-013-0831-8 | 1. Efficacy at 1, 2, 3, 4 and 5 year Percutaneous cryoablation for RCC = 99.2, 99.2, 98.9, 98.5, and 97.0%, respectively. 2. The cancer-specific 5-year survival was 100%. | CT-guided percutaneous cryoablation for renal cancer offers very high efficacy, approaching that of the gold standard, with a more favorable safety profile. |
| Psutka, Sarah P et al. “Long-term oncologic outcomes after radiofrequency ablation for T1 renal cell carcinoma.” European urology vol. 63,3 (2013): 486-92. doi:10.1016/j.eururo.2012.08.062 | 1. Tumor stage - T1a: 143 (77.3%) or T1b: 42 (22.7%). 12 local recurrences (6.5%)[6 recurrences in T1a disease (4.2%) and 6 in T1b disease (14.3%) (p = 0.0196)]. 2. Median time to recurrence was 2.5 yr. 3. Local salvage RFA was performed in six patients, of whom five remain disease free at 3.8-yr median follow-up. | In poor surgical candidates, RFA results in durable local control and low risk of recurrence in T1a RCC. Higher stage correlates with a decreased disease-free survival. Long-term surveillance is necessary following RFA. Patient selection based on tumor characteristics, comorbid disease, and life expectancy is of paramount importance. |
| Takaki, Haruyuki et al. “Midterm results of radiofrequency ablation versus nephrectomy for T1a renal cell carcinoma.” Japanese journal of radiology vol. 28,6 (2010): 460-8. doi:10.1007/s11604-010-0451-z | 1. Overall survival at 5 years RF group = 75% Radical nephrectomy = 100% Partial nephrectomy = 100% at 3 years 2. Disease-free survival (DFS) at 5 years RF group = 98.0% Radical nephrectomy = 95.0% (P = 0.72) and Partial nephrectomy = 75.0% at 3 years (P = 0.13) 3. Percent decrease in the GFR RF group = 7.9% Radical nephrectomy = 29.0% (P = < 0.001) and Partial nephrectomy = 11.5% (P = 0.73) | RF ablation provides RCC-related and DFS comparable to that found after nephrectomy with little loss of renal function. |
| Zagoria, Ronald J et al. “Oncologic efficacy of CT-guided percutaneous radiofrequency ablation of renal cell carcinomas.” AJR. American journal of roentgenology vol. 189,2 (2007): 429-36. doi:10.2214/AJR.07.2258 | Tumor size smaller than 3.7 cm was significantly associated with achieving complete tumor eradication (p < 0.001). | CT-guided percutaneous radiofrequency ablation is a safe method to treat small RCCs. This study indicates that radiofrequency ablation can reliably eradicate RCCs smaller than 3.7 cm. Treatment of larger RCCs will result in an increased risk of residual RCC. |
| Katsanos, K et al. “Systematic review and meta-analysis of thermal ablation versus surgical nephrectomy for small renal tumours.” Cardiovascular and interventional radiology vol. 37,2 (2014): 427-37. doi:10.1007/s00270-014-0846-9 | Thermal ablation group = percutaneous or laparoscopic application of radiofrequency or microwave Surgical nephrectomy = open or laparoscopic 1. Overall complication rate Significantly lower in the ablation group (7.4 vs. 11%; RR: 0.55, 95% confidence interval [CI]: 0.31-0.97, p = 0.04) 2. Postoperative decline of eGFR Higher in case of nephrectomy (mean difference: -14.6 ml/min/1.73 m(2), 95% CI: -27.96 to -1.23, p = 0.03 3. Local recurrence rate Same in both groups (3.6 vs. 3.6%; RR: 0.92, 95% CI: 0.4-2.14, p = 0.79) 4. Disease-free survival (DFS) Similar up to 5 years (HR: 1.04, 95% CI: 0.48-2.24, p = 0.92) | Thermal ablation of small renal masses produces oncologic outcomes similar to surgical nephrectomy and is associated with significantly lower overall complication rates and a significantly less decline of renal function. More randomized, controlled trials are necessary. |
| Kunkle, David A, and Robert G Uzzo. “Cryoablation or radiofrequency ablation of the small renal mass : a meta-analysis.” Cancer vol. 113,10 (2008): 2671-80. doi:10.1002/cncr.23896 | 1. Repeat ablation was performed more often following RFA(8.5% versus 1.3%, P<0.0001) 2. Rates of local tumor progression were significantly higher for RFA(12.9% versus 5.2%, P<0.0001) compared to cryoablation. 3. Local tumor progression - significantly higher in RFA group univariate(P=0.001) multivariate regression analysis(P=0.003). 4. Metastasis was reported less frequently for cryoablation (1.0%) versus RFA(2.5%)(P=0.06). Cryoablation was usually performed laparoscopically(65%) whereas 94% of RFA lesions were aproached percutaneously. | Ablation of SRMs is a viable strategy based on short-term oncologic outcomes. While extended oncologic efficacy remains to be established for ablation modalities, these data suggest that cryoablation results in fewer retreatments, improved local tumor control, and may be associated with a lower risk of metastatic progression compared to RFA |