Microwave ablation of focal hepatic malignancies regardless of size: A 9-year retrospective study of 64 patients

• MWA appears to be a more effective treatment for larger tumors compared with RFA.
• Intraoperative MWA outperformed percutaneous MWA.
• Complications related to MWA of liver tumors were minor and self limited.

PurposeTo retrospectively evaluate the safety and efficacy of microwave ablation (MWA) as treatment for single, focal hepatic malignancies.Materials and MethodsInstitutional review board approval was obtained for this HIPAA-compliant study. From December 2003 to May 2012, 64 patients were treated with MWA for a single hepatic lesion, in 64 sessions. Hepatocellular carcinoma (HCC) was treated in 25 patients (geometric mean tumor size, 3.33-cm; 95% CI, 2.65–4.18-cm; range, 1.0–12.0-cm), metastatic colorectal cancer (CRC) was treated in 27 patients (geometric mean tumor size, 2.7-cm; 95% CI, 2.20–3.40-cm; range, 0.8–6.0-cm), and other histological-types were treated in 12 patients (geometric mean tumor size, 3.79-cm; 95% CI, 2.72–5.26-cm; range, 1.7–8.0-cm). Kaplan–Meier (K–M) method was used to analyze time event data. Chi-square and correlation evaluated the relationship between tumor size and treatment parameters.ResultsTechnical success rate was 95.3% (61/64). Treatment parameters were tailored to tumor size; as size increased more antennae were used (p < 0.001), treatment with multiple activations increased (p < 0.028), and treatment time increased (p < 0.001). There was no statistically significant relationship between time to recurrence and tumor size, number of activations, number of antennae, and treatment time.At one-year, K–M analysis predicted a likelihood of local recurrence of 39.8% in HCC patients, 45.7% in CRC metastases patients, and 70.8% in patients with other metastases. Median cancer specific survivals for patients were 38.3 months for HCC patients, 36.3 months for CRC metastases, and 13.9 months for other histological-types.Complications occurred in 23.4% (15/64) of sessions.ConclusionIn our sample, tumor size did not appear to impact complete ablation rates or local recurrence rates for focal hepatic malignancies treated with MWA.