ASCO GU 2020: Nonsurgical Local Treatment Options and Their Limits: Percutaneous Ablation

San Francisco, CA (UroToday.com) To conclude the session on treatment selection for localize renal tumors at GU ASCO 2020, Dr. David Liu, PhD, from the University of British Columbia discussed percutaneous ablation as a nonsurgical treatment option for patients with renal cell carcinoma (RCC). Dr. Liu notes that thermal ablative strategies have been used for nearly 25 years, dating back to in vivo experiments in the mid-90’s for radiofrequency tumor ablation lead by Professor Alexandre Zlotta. Since then, there have been evolving indications:

  • From 2000-2005 (the non-operative patient era): comorbid conditions and non-surgical candidates
  • From 2005-2014 (the extreme nephron sparing era): patients with renal insufficiency and those with syndromes (ie. VHL)
  • From 2014 – present (the curative intent era): patients with lesions <3 cm and comparable to partial nephrectomy

Dr. Liu notes that there are several reasons to ablate tumors, including: decreased complications, decreased blood loss, decreased admission time, decreased open surgical conversion, and perhaps improved cost efficacy. Alternatively, there are also reasons to not ablate, including: higher recurrence rates, tumor location and size, lack of local expertise, multidisciplinary management, and increased need for surveillance.

A systematic review and meta-analysis published in 2016 summarized the comparative effectiveness among patients undergoing active surveillance, thermal ablation, radical nephrectomy or partial nephrectomy.1 Among 107 studies identified, the majority assessed T1 tumors, as no active surveillance or thermal ablation stratified outcomes of T2 tumors. Cancer specific survival was excellent among all management strategies with a median 5-year survival 95% for all modalities. Local recurrence-free survival was inferior for thermal ablation with one treatment but reached equivalence to other modalities after multiple treatments. Overall survival rates were similar among management strategies and varied with age and comorbidity. End-stage renal disease rates were low for all strategies (0.4%-2.8%), however radical nephrectomy was associated with the largest decrease in eGFR rate and highest incidence of chronic kidney disease. Thermal ablation offered the most favorable perioperative outcomes, whereas partial nephrectomy showed the highest rates of urological complications. but overall rates of minor/major complications were similar among interventions.

Investigators have also looked to the SEER-Medicare database to compare effectiveness of thermal ablation, surgical resection and active surveillance for T1a RCC.2 There were 10,218 patients with T1aN0M0 RCC as first primary cancer diagnosis – cancer-specific survival significantly differed in the partial nephrectomy versus radical nephrectomy (p < 0.001) groups, the active surveillance versus thermal ablation (p = 0.03), and active surveillance versus partial nephrectomy (p = 0.002) groups. There were no significant differences when thermal ablation was compared with partial nephrectomy or radical nephrectomy, with 9-year cancer-specific survival rates of 96.4% versus 96.3% (partial nephrectomy vs thermal ablation, p = 0.07) and 96.1% versus 96.0% (radical nephrectomy vs thermal ablation, p = 0.14), respectively.

The society position statements are quite clear that thermal ablative therapies are an option for patients with small renal masses. The NCCN guidelines ablative techniques should be offered as a primary treatment in their updated 2020 guidelines. Specifically, NCCN says that thermal ablation is an option for masses ≤ 3cm, but may also be an option for larger masses in select patients. The ASCO guidelines suggest that percutaneous thermal ablation should be considered an option for patients who possess tumors such that compete will be achieved. Furthermore, ASCO recommends that a biopsy should be performed before or at the time of the ablation. Finally, the AUA notes that physicians should consider thermal ablation as an alternative approach for the management of cT1a renal masses <3 cm in size; a percutaneous technique is preferred over a surgical approach whenever feasible.

Regarding patient selection, there are several metrics available for scoring tumor complexity, including the PADUA score, and the RENAL nephrometry. The lesions that are considered challenging for ablation include those that are: too big (>3 cm), too many (> 3), too peripheral, not well-defined, too central, and are recurrent/failed. The following figure illustrates several important nuances for ablative therapy:3
ASCOGU_MaximumTumorDiameter.png

According to Dr. Liu, there are no clear prognosticators relating to RCC subtype and ablation, and there is no significant alteration of renal function post-ablation. The main prognosticator of failure/recurrence is size of the lesion, and adjacent cortical structures may effect technical ability and complication rates.

Dr. Liu concluded with several take-home points from his presentation of ablative therapies for RCC:

  • Technology is not as important in the modern era
  • Percutaneous results are less morbid
  • The AUA, ASCO, and NCCN all endorse ablative therapies
  • Currently, there is no clear guidance as to which patients with T1a tumors do better
  • A multidisciplinary approach is essential for optimizing care

Presented by: David Liu, PhD, University of British Columbia, Vancouver, BC, Canada

Written By: Zachary Klaassen, MD, MSc – Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, Twitter: @zklaassen, at the 2020 Genitourinary Cancers Symposium, ASCO GU #GU20, February 13-15, 2020, San Francisco, California

References:

  1. Pierorazio PM, Johnson MH, Patel HD, et al. Management of renal masses and localized renal cancer: Systematic review and meta-analysis. J Urol 2016 Oct;196(4):989-999.
  2. Xing M, Kokabi N, Zhang D, et al. Comparative effectiveness of thermal ablation, surgical resection, and active surveillance for T1a renal cell carcinoma: A Surveillance, Epidemiology, and End Results (SEER)-Medicare-linked Population Study. Radiology 2018 Jul;288(1):81-90.
  3. Maxwell AWP, Baird GL, Iannuccilli JD, et al. Renal cell carcinoma: Comparison of RENAL Nephrometry and PADUA Scores with maximum tumor diameter for prediction of local recurrence after thermal ablation. Radiology 2017 May;283(2):590-597.
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