Abstract No. 90 Long-Term Outcomes of PET-Guided Microwave Ablation of Breast Cancer Liver Metastases

To assess the long-term outcomes of patients with breast cancer liver metastases treated with PET-guided microwave ablation and analyze variables affecting survival. This is an IRB-approved retrospective review. From March 2012 to October 2017 a total of 20 patients (ages 39-83, mean 53.9years) with breast cancer liver metastases underwent FDG-18-PET-guided microwave ablation using split dose technique. The number of lesions ranged from 1 to 3. Lesions ranged in size from 1.2-4.6 cm. Margin assessment at time of ablation was performed using PET overlay. Independent variables assessed included number of lesions, lesion size > 3 cm, hormone receptor status, presence of margins >10 mm, and presence of extrahepatic disease. Univariate analysis of overall survival (OS) was performed through Kaplan-Meier survival curves and log-rank tests. Technical efficacy was 95% with complete metabolic response in 19 of 20 patients. Median OS was 46.3 months. 1, 3 and 5 year survival was 93%, 56% and 48% respectively. There was a statistically significant increase in OS when ablation margins were >10 mm (63.9 months vs 23.8 months, P < 0.05). Other factors which significantly decreased OS were multiplicity of lesions (P = 0.05) and presence of extrahepatic disease (P = 0.028). Lesion size >3 cm and hormone receptor status did not significantly impact OS. PET-guided microwave ablation of breast cancer liver metastases is most effective with a margin >10 mm in patients with a solitary lesion and no extrahepatic disease. PET guidance may be an effective method for treating larger lesions >3 cm compared with conventional image guided ablation techniques.