Abstract No. 30 Safety and Efficacy of Liver-Directed Therapies for Non-Small Cell Lung Cancer Metastatic to the Liver: A Retrospective Cohort Analysis of Patients Treated with Microwave Ablation and Yttrium-90 Treatment

To evaluate safety and efficacy of liver-directed therapy (LDT), including microwave ablation (MWA) and yttrium-90 (Y90), in the treatment of limited liver metastases (LM) secondary to non-small cell lung cancer (NSCLC). Retrospective study including all patients with NSCLC who underwent MWA or Y90 of < 5 LM with intention to treat all liver disease. Twenty-five patients underwent LDT in 27 treatments (17 MWA sessions of 20 lesions; 10 Y90 sessions), from 10/2013-7/2022. MWA was performed with Neuwave MWA (Ethicon, Raritan, NJ) and/or Emprint MWA (Medtronic, Minneapolis, MN) systems. Y90 was performed with resin (SIR-Spheres Y-90, Sirtex, Woburn, MA) or glass microspheres (TheraSphere Y-90, Boston Scientific, Marlborough, MA). Local tumor progression-free survival (LTPFS) and overall survival (OS) were estimated using Kaplan–Meier method; differences between groups were estimated using Cox proportional hazards model and the logrank test. Complications were graded according to Common Terminology Criteria for Adverse Events (CTCAE) v5.0. Patient and tumor details are in Table 30.1. Tumor progression after MWA was 65% (13/20) with median length of follow-up of 50.9 months. Median LTPFS for tumors treated with MWA was 16.33 (95%CI: 3.67-44.1) months. Median OS for tumors treated with MWA was 36.5 (95%CI:15-65.83) months. Predictors of OS after MWA were age (HR:1.23, 1.09-1.39, p=0.001). Tumor progression after Y90 was 50% (5/10) with median length of follow-up of 13.33 months. Median LTPFS for tumors treated with Y90 was 4.53 (95%CI:0.9-NR) months. Median OS for tumors treated with Y90 was 8.87 (6.77-NR) months. In the Y90 group, patients with 2-5 lesions had a lower OS compared with patients with 1 lesion (8.33 [95%CI:6.8-NR] months vs 14.33 [95%CI:6.77-NR] months, p=0.04). Complications within 30 days occurred in 8/17 (47.1%) MWA sessions and 4/10 (40%) Y90 sessions. Severe complications (CTCAE grade ³3) occurred after 2/17 (11.8%) of MWA sessions and included pulmonary embolus and severe abdominal pain; no severe complications were associated with Y90. LDT provides safe local control of NSCLC metastases which have metastasized to liver. MWA was associated with long LTPS and OS.