title: A retrospective comparison of microwave ablation vs. radiofrequency ablation for colorectal cancer hepatic metastases.
abstract: BACKGROUND
  Microwave (MWA) and radiofrequency ablation (RFA) are the most commonly used techniques for ablating colorectal-liver metastases (CRLM). The technical and oncologic differences between these modalities are unclear.
  
  
  METHODS
  We conducted a matched-cohort analysis of patients undergoing open MWA or RFA for CRLM at a tertiary-care center between 2008 and 2011; the primary endpoint was ablation-site recurrence. Tumors were matched by size, clinical-risk score, and arterial-intrahepatic or systemic chemotherapy use. Outcomes were compared using conditional logistic regression and stratified log-rank test.
  
  
  RESULTS
  We matched 254 tumors (127 per group) from 134 patients. MWA and RFA groups were comparable by age, gender, median number of tumors treated, proximity to major vessels, and postoperative complication rates. Patients in the MWA group had lower ablation-site recurrence rates (6% vs. 20%; P < 0.01). Median follow-up, however, was significantly shorter in the MWA group (18 months [95% confidence interval 17-20] vs. 31 months [95% confidence interval 28-35]; P < 0.001). Kaplan-Meier estimates of ablation-site recurrence at 2 years were significantly lower for the lesions treated with MWA (7% vs. 18%, P: 0.01).
  
  
  CONCLUSIONS
  Ablation-site recurrences of CRLM were lower with MWA compared with RFA in this matched cohort analysis. Longer follow-up time in the MWA may increase the recurrence rate; however, actuarial local failure estimations demonstrated better local control with MWA.
authors.affiliation: Department of Hepatopancreatobiliary Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
authors.forename: Camilo
authors.initials: C
authors.lastname: Correa-Gallego
authors.forename: Yuman
authors.initials: Y
authors.lastname: Fong
authors.forename: Mithat
authors.initials: M
authors.lastname: Gonen
authors.forename: Michael I
authors.initials: MI
authors.lastname: D'Angelica
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Allen
authors.forename: Ronald P
authors.initials: RP
authors.lastname: DeMatteo
authors.forename: William R
authors.initials: WR
authors.lastname: Jarnagin
authors.forename: T Peter
authors.initials: TP
authors.lastname: Kingham
mesh_terms: D000368:Aged; D017115:Catheter Ablation; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology / Q000628:therapy*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008113:Liver Neoplasms / Q000401:mortality / Q000556:secondary / Q000628:therapy*; D008297:Male; D008872:Microwaves / Q000627:therapeutic use*; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate