“The most serious potential complications associated with MWA are bleeding and nontarget organ injury,” said interventional radiologist Ronald Arellano, MD, associate professor of radiology at the Massachusetts General Hospital, in Boston. 

“The same potential complications also apply to any of the ablation technologies — radiofrequency ablation and cryoablation,” Dr Arellano told Cancer Therapy Advisor.

The overall risk of serious complication is lower than 5%, and mortality rates are lower than those associated with surgery, he said. MWA is “equally effective” compared with cryoablation or radiofrequency ablation, he and others have concluded.7

MWA complications depend on the tumor’s size and location within the kidney, Dr Arellano noted. 

“Treatment of tumors that are near the central collecting system may be at risk of injury to the urinary collecting system,” he said. “However, there are ancillary maneuvers that can be employed to help minimize this risk. This involves placement of a small tube in the ureter immediately prior to the procedure and perfusing saline solution into the collecting system to help maintain normal temperatures during treatment.”

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Tumors growing on the kidney’s outer surface are also sometimes close to bowel tissue, in which case, hydrodissection is employed to move the bowel away from the target tissue: a needle is placed between tumor and bowel and is then used to inject fluid between the two, pushing them apart, Dr Arellano said.

“Even for practitioners who have considerable experience using other ablation modalities, a learning curve exists in appreciating the potential complications from renal MWA,” cautioned the Mayo team.“Although MWA will increasingly be incorporated into the management of renal masses, we encourage prudence in its application to central renal masses.”

References

  1. Thompson SM, Schmitz JJ, Thompson RH, et al. Introduction of microwave ablation into a renal ablation practice: valuable lessons learned[published online November 5, 2018]. AJR Am J Roentgenol. 2018:1-9. doi: 10.2214/AJR.18.19775 
  2. Choi SH, Kim JW, Kim JH, Kim KW. Efficacy and safety of microwave ablation for malignant renal tumors: an updated systematic review and meta-analysis of the literature since 2012Korean J Radiol. 2018;19(5):938-949.
  3. Wells SA, Wheeler KM, Mithqal A, Patel MS, Brace CL, Schenkman NS. Percutaneous microwave ablation of T1a and T1b renal cell carcinoma: short-term efficacy and complications with emphasis on tumor complexity and single session treatmentAbdom Radiol (NY). 2016;41(6):1203-1211.
  4. Maciolek KA, Abel EJ, Best SL, et al. Percutaneous microwave ablation for local control of metastatic renal cell carcinomaAbdom Radiol (NY). 2018;43(9):2446-2454.
  5. Hao G, Hao Y, Cheng Z, et al. Local tumor progression after ultrasound-guided percutaneous microwave ablation of stage T1a renal cell carcinoma: risk factors analysis of 171 tumors[published online May 28, 2018]. Int J Hyperthermia.2018:1-9. doi: 10.1080/02656736.2018.1475684
  6. Klapperich ME, Abel EJ, Ziemlewicz TJ, et al. Effect of tumor complexity and technique on efficacy and complications after percutaneous microwave ablation of stage T1a renal cell carcinoma: a single-center, retrospective studyRadiology.2017;284(1):272-280. 
  7. Zhou W, Arellano RS. Thermal ablation of T1c renal cell carcinoma: a comparative assessment of technical performance, procedural outcome, and safety of microwave ablation, radiofrequency ablation, and cryoablationJ Vasc Interv Radiol. 2018;29(7):943-951.