Percutaneous cryoablation of breast cancer metastases: Analysis of long-term single center experience, efficacy and outcomes.

e13105 Background: Percutaneous image-guided cryoablation is a minimally invasive loco-regional treatment modality with wide availability and advantages of minimal sedation, short recovery, and ability to continue concurrent systemic therapy. However, there is a paucity of data about its long-term effects in the treatment of metastatic breast cancer despite evidence suggesting a potential survival advantage with loco-regional therapy for oligo-metastatic disease. Methods: We conducted retrospective analysis of patients who underwent CT-guided percutaneous cryoablation for metastatic breast cancer and had at least 1 follow up post cryoablation. Patient data including demographics, cancer treatment history and outcomes were extracted by chart review after IRB approval. Descriptive analyses of overall survival (OS), progression-free survival (PFS), and time to next-line treatment (TTNL) was performed. Results: The study encompassed 37 metastatic breast cancer patients who underwent cryotherapy between 2004-2021. These ablation procedures targeted various metastatic sites, which included the liver, lung, renal, lymph nodes, subcutaneous nodules, and bone. Their median age at the time of cryoablation was 58 years (range: 34-90). Among them, 46% had triple-negative breast cancer (TNBC), 41% were HR+/HER2-, and 8% were HER2+. Prior to first cryoablation procedure, 59% of patients had received more than one line of systemic therapy, and 73% were actively undergoing systemic treatment. The median size of the metastatic lesions treated with cryoablation was 1.8 cm (range: 0.4-6.5 cm). The most frequent site for cryotherapy was the liver (38%), followed by lymph nodes (30%). For the entire cohort, median PFS, TTNL, and OS were 7.1, 14, and 65.7 months, respectively. Subgroup analysis revealed mPFS of 3.1, 7.4 and 14.2 months for TNBC, Her2+ and HR+/Her2- cohorts respectively. Subgroup analysis for OS was not reported due to the small number of events and premature follow up time. Among the 27 patients who experienced disease progression, the majority (74%) had distant progression, with 22% occurring within the same organ but outside the ablation zone. Local recurrence within the ablation zone was rare, observed in only 4% of cases. Conclusions: Percutaneous image-guided cryoablation of metastatic breast cancer lesions demonstrated durable local response, prolonged PFS, TTNL and OS. Future studies investigating cryoablation as part of a multidisciplinary treatment approach for patients with metastatic breast cancer are worthwhile to confirm disease control rate and improvement in survival.