title: Needle track seeding after percutaneous microwave ablation of malignant liver tumors under ultrasound guidance: analysis of 14-year experience with 1462 patients at a single center.
abstract: OBJECTIVE
  To determine the incidence and risk factors associated with needle tract seeding after percutaneous microwave ablation (MWA) of liver cancer under ultrasound guidance.
  
  
  METHODS
  Over a 14-year period, a total of 1462 patients with 2530 malignant nodules were treated by MWA. The influence of age, sex, Child-pugh classification, tumor size, tumor position, previous biopsy, insertion number and antenna type on the risk of neoplastic seeding was assessed. The survival of seeding patients after the MWA was analyzed.
  
  
  RESULTS
  Eleven patients with 12 nodules (0.47% per tumor, 0.75% per patient) were identified with needle tract seeding with an interval time of 6-37 (median 10) months after MWA. The mean size of the seeding nodule was 2.3 ± 0.7 cm (from 1.3 to 3.9 cm). Only previous biopsy was significantly associated with neoplastic seeding (P=0.02). All the seeding lesions were successfully treated by resection, MWA, radiation or high intensity focus ultrasound. The median survival period of the 11 patients after the MWA was 36.0 months. The cumulative survival rates of the 11 patients after the MWA at 1-, 2-, 3-, 4- and 5-year were 90.9%, 72.7%, 62.3%, 31.2% and 15.6%, respectively.
  
  
  CONCLUSIONS
  The results showed that the neoplastic seeding was a low risk complication of percutaneous MWA of liver cancer and was considered acceptable in general.
authors.affiliation: Department of Interventional Ultrasound, Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China. yu-jie301@hotmail.com
authors.forename: Jie
authors.initials: J
authors.lastname: Yu
authors.forename: Ping
authors.initials: P
authors.lastname: Liang
authors.forename: Xiao-ling
authors.initials: XL
authors.lastname: Yu
authors.forename: Zhi-gang
authors.initials: ZG
authors.lastname: Cheng
authors.forename: Zhi-yu
authors.initials: ZY
authors.lastname: Han
authors.forename: Bao-wei
authors.initials: BW
authors.lastname: Dong
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017115:Catheter Ablation / Q000295:instrumentation* / Q000706:statistics & numerical data*; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality* / Q000601:surgery*; D008137:Longitudinal Studies; D008297:Male; D008872:Microwaves / Q000627:therapeutic use; D008875:Middle Aged; D009339:Needles / Q000706:statistics & numerical data*; D009366:Neoplasm Seeding; D011183:Postoperative Complications; D015995:Prevalence; D018570:Risk Assessment; D012307:Risk Factors; D025321:Surgery, Computer-Assisted / Q000401:mortality*; D016019:Survival Analysis; D015996:Survival Rate; D016896:Treatment Outcome; D014463:Ultrasonography / Q000401:mortality