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

To determine the incidence and risk factors associated with needle tract seeding after percutaneous microwave ablation (MWA) of liver cancer under ultrasound guidance.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.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.The results showed that the neoplastic seeding was a low risk complication of percutaneous MWA of liver cancer and was considered acceptable in general.