Presentation Authors: Daniel D. Shapiro*, Sara L. Best, Shane A. Wells, Timothy J. Ziemlewicz, Meghan G. Lubner, J. Louis Hinshaw, Fred T. Lee, David F. Jarrard, Kyle A. Richards, Tracy M. Downs, Tudor Borza, Glenn O. Allen, Stephen Y. Nakada, E. Jason Abel, Madison, WI
Introduction: Percutaneous thermal ablation is a minimally invasive nephron-sparing treatment for RCC that provides an alternative to surgery for co-morbid patients. Most cryotherapy and RFA studies have focused on treatment of small RCC but treatment of larger tumors may be facilitated with high power microwave ablation (MWA). The purpose of this study is to compare oncologic outcomes for RCC patients with clinical T1b tumors following surgery or MWA.
Methods: Comprehensive data was collected for consecutive RCC patients with cT1b tumors following treatment with MWA (NeuWave Medical), partial nephrectomy (PN) or radical nephrectomy (RN). Locally advanced or metastatic tumors were excluded. Patients were offered MWA after failing (growth >5mm/year) or refusing active surveillance. Univariate and multivariate Cox analysis evaluated associations between variables and survival outcomes.
Results: A total of 326 patients (41 MWA, 74 PN and 211 RN) were identified between 2000-2017. Patients treated with MWA were older (p < 0.001) and more comorbid (p < 0.001) vs. surgery patients. No difference identified in gender, race, BMI, eGFR, and tumor diameter. Median follow-up was 41 months (IQR 14-81 months)._x000D_
Local recurrence was identified in 3, 1, and 1 patients following MWA, PN, and RN. 5-year local recurrence free survival was lower following MWA (91.2%) vs. PN (97.9%) or RN (99.2%); p=0.001). Three patients with local recurrence following MWA were treated with repeat ablation and had no evidence of residual disease after median of 29 months from the second ablation. _x000D_
Progression to metastasis was identified in 0, 4, and 19 patients treated with MWA, PN, and RN. No difference in 5-year metastasis free survival was identified following MWA (100%) PN (91.8%) and RN (87.2%), p=0.793. _x000D_
No difference was identified for 5- yr CSS among 3 treatments, p=0.90. Estimated 5-year OS was lower for MWA (80%) vs PN (97%; p=0.006) and RN (93%; p=0.02). _x000D_
Treatment with MWA was not associated with progression to metastasis. Independent predictors of metastatic progression included tumor grade and sarcomatoid features (p < 0.01).
Conclusions: MWA for cT1b RCC has similar oncologic outcomes vs surgery and may be an alternative treatment for those who are high surgical risk due to comorbidity or patients who refuse surgery.