(UroToday.com) Dr. Ithaar Derweesh, from University of California San Diego, School of Medicine started the debate with arguments in support of thermal ablation (TA) for patients with small renal masses. While the overall share of thermal ablation in the management of renal masses only represents 10% of the urologist’s armamentarium, a recent SEER database analysis showed an up to 2-3 times increase in the utilization of radiofrequency- and cryo-ablation between 2006-2019. However, a study by Patel et al., looking at the utilization of renal mass biopsy in patients with localized renal cell carcinoma based on the National Cancer Database showed that despite an overall increase in biopsy rate, 37% of the ablation patients still don’t get biopsied pre-operatively.
As per the American Urological Association Guidelines, thermal ablation (either in the form of radiofrequency or thermal ablation) remains an alternate approach for the management of cT1a solid renal masses with the largest diameter < 3 cm. Going beyond the guideline recommendations, a previous study by Brassier and colleagues showed that when compared to partial nephrectomy (PN), percutaneous ablation was associated with lower post-operative complications (OR=0.22; p=0.006) and a smaller drop in the estimated Glomerular Filtration Rate (eGFR) (4. Moreover, in this cohort of 81 patients followed up for a 23-month period, there was no significant difference in disease recurrence (HR=0.72, p=0.61), localized recurrence (HR=1.51, p=0.59) or distant metastasis (HR=0.19, p=0.09) when using TA as opposed to PN.
Dr. Derweesh also emphasized the importance of renal mass biopsy for preoperative risk stratification before PN or TA. Low grade injury and non-clear cell renal cell carcinoma histology have been shown to have more favorable outcomes if thermal ablation is performed. On the other hand, a higher grade and clear cell histology is associated with a higher chance of recurrence and progression.
Dr. Jeffrey Cadeddu from the University of Texas Southwestern System Medical Center has pointed out that radiofrequency ablation is a safe and effective treatment option for small renal masses less than 3 cm in diameter. A 10-year follow-up revealed good long-term oncologic outcomes, with no recurrence developing after 5 years. For tumors greater than 3 cm, however, the outcomes were found to be significantly poorer.
Thermal ablation is also associated with overall better emotional functioning, role functioning, fatigue, pain, appetite, and dyspnea. The only area of similar outcomes for thermal ablation and percutaneous nephrolithotomy was bowel dysfunction (i.e., constipation and diarrhea). Moreover, when comparing the renal parenchymal volume preservation between partial nephrectomy, cryoablation and radiofrequency ablation, thermal ablation (regardless of its kind was associated with less renal parenchymal volumes lass than partial nephrectomy. When sub-stratifying the thermal ablation group in cryo and radio-frequency ablation, no difference was noted between the two groups.
Dr. Cadeddu has also pointed out that Gahan et al. previously showed the benefit of radiofrequency ablation even in a younger population (mean age 57). The 5 & 10-year disease-free survival was 94% and the 5&10 year overall survival was 96% and 91% respectively.
PRO-Partial Nephrectomy:As Dr. Alexander Kutikov, MD, from Fox Chase Cancer Center pointed out, the current standard of care for amenable renal mass lesions is PN. In truth, TA only offers three theoretical benefits over partial nephrectomy:
- It mitigates periprocedural risk.
While the panelist could not argue that TA is more risky than a surgical intervention, it is worth pointing out that the procedure is not risk-free.
- It preserves renal function.
But since we cannot agree that radical versus partial nephrectomy has a significant effect on renal function, how could we be sure that that’s the case for partial nephrectomy versus thermal ablation?
- It affords uncompromised oncological control.
The panelist referred to a cryotherapy study, which cites an overall survival at 18 years of 72% for percutaneous cryoablation, 49% for partial nephrectomy, and 43% for radical nephrectomy. As thoroughly explained by Dr. Kutikov, when looking at the data, one can clearly see that this statement is based on the results of a single-center study comparing the outcomes of cryotherapy with the NCDB administrative data. But as correctly pointed out by the author, such data is flawed by a combination of selection bias, unmeasured confounders, differences in treatment protocols and follow-up, statistical limitations, and highly debatable methodological assumptions. As such, solely focusing your marketing strategy based on the results of a single study, with low evidence and significant methodological challenges, may be perceived as disingenuous.
But in fact, as pointed out by Dr. Kutikov there is actually limited data on renal mass ablation. Moreover, the basis of the surgery vs ablation comparison is unfair as the two target populations are greatly different. Surgery patients are on average 10 years younger, have fewer comorbidities, and are thus less likely to die during follow-up despite being followed for a longer period of time8. Moreover, the tumors included in the two groups are also different, with more aggressive tumors often requiring surgery8.
Dr. Kutikov also paid tribute to the great contribution that Dr. Anil Kappor, who has sadly passed away, has made in the field of renal oncology. In a multi-center study comparing percutaneous thermal ablation therapy with partial nephrectomy of cT1a tumors, Dr. Kappor’s team showed that indeed, partial nephrectomy was associated with superior oncological outcomes.
Dr. Robert Uzzo, from Fox Chase Center has pointed out that active surveillance is non-inferior to thermal ablation…but has not yet been proven to be better either (although it has a superior billing code). His recommended logical approach? Start with active surveillance and proceed to surgery if needed.
Conclusions:Ultimately, the choice between partial nephrectomy or thermal ablation should be made in consultation with a qualified medical professional. When asked by Dr. Ball, from the National Cancer Institute, whether they perform partial nephrectomy or thermal ablation, all panelists admitted to incorporating both procedures in their clinical practice. The jury is still out on which approach is definitively better, as both have their own benefits and drawbacks.
Presented by:- Ithaar Derweesh, MD, University of California San Diego, School of Medicine
- Jeffrey Cadeddu, MD, University of Texas Southwestern System Medical Center
- Alexander Kutikov, MD, FACS, Fox Chase Cancer Center
- Robert Uzzo, MD, MBA, FACS, from Fox Chase Cancer Center
Written by: Andrei Cumpanas, MD, Department of Urology, University of California Irvine, @andreicumpanas on Twitter during the 2023 American Urological Association (AUA) Annual Meeting, Chicago, IL, April 27 – May 1, 2023