Liver Metastases-directed Therapy in the Management of Oligometastatic Breast Cancer

Introduction: In the context of metastatic breast cancer, dissemination to the liver is a frequent occurrence. We aimed to evaluate the outcome and toxicity of metastatic breast cancer with liver oligometastases treated with metastases-directed therapies (MDTs), including surgery, stereotactic body radiation therapy, or thermal ablation (radiofrequency or microwaves). Patients and Methods: We included patients with diagnosis of 1 to 5 liver metastases. Selection criteria included also age > 18 years; Eastern Cooperative Oncology Group performance status 0 to 2; absence of extra-hepatic disease or other controlled metastatic sites. Endpoints were liver progression-free survival (LPFS), progression-free survival (PFS), and overall survival. Results: A total of 72 patients were included. Previous local treatments were performed in 13 (18.1%) patients, whereas systemic therapy was used in 81.9% of cases. Treatment of choice was stereotactic body radiation therapy in 54 (75%) patients followed by surgery (13 patients; 18%) and thermal ablation (5 patients; 7%). With a median follow-up of 26.2 months, LPFS at 1 and 2 years was 52.4% and 38.8%, respectively. The number of metastases predicted LPFS (hazard ratio [HR], 1.70; P =.004). Rates of PFS were 38.7% and 22% at 1 and 2 years, respectively. Systemic therapy before MDT (HR, 2.89; P =.016) was correlated with PFS. Overall survival at 1 and 2 years was 95.5% and 76.9%, respectively. Human epidermal growth factor receptor 2 status correlated with survival (HR, 1.82; P =.010). Conclusion: Combination of systemic therapy with liver MDT in oligometastatic breast cancer results in durable disease control in a significant proportion of patients. Tumor biology, prior treatment, and extent of disease may be useful to guide the decision to add MDT to standard therapy.