Liver Resection after Disease Control with Abemaciclib for Solitary Liver Metastasis from Breast Cancer: A Case Report.

INTRODUCTION: Liver metastases from breast cancer are associated with a poorer prognosis than bone or soft tissue metastases. In hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative recurrent or metastatic breast cancer, endocrine therapy combined with cyclin-dependent kinase 4/6 (CDK4/6) inhibitors has been established as the standard of care. Abemaciclib has demonstrated favorable efficacy in phase III clinical trials and is considered an important option for long-term disease control. With recent advances in systemic therapy, an increasing number of patients achieve sustained disease control; however, prolonged treatment may lead to impaired QOL, financial burden, and the need for long-term therapy. Consequently, the role of local treatment in carefully selected patients with well-controlled disease has increasingly been discussed. Here, we report a case of breast cancer with postoperative recurrent solitary liver metastasis in which disease control was achieved with endocrine therapy plus abemaciclib, followed by liver resection, resulting in long-term recurrence-free survival.

CASE PRESENTATION: A 45-year-old woman with HR-positive, HER2-negative breast cancer underwent breast-conserving surgery followed by adjuvant chemotherapy, radiotherapy, and endocrine therapy. Five years after surgery, follow-up CT revealed a solitary liver lesion. Percutaneous biopsy demonstrated adenocarcinoma consistent with a solitary liver metastasis from breast cancer. Combination therapy with a luteinizing hormone-releasing hormone agonist, fulvestrant, and abemaciclib was initiated. Although dose reduction of abemaciclib was required because of grade 3 neutropenia, stable disease was maintained for approximately 1 year. Given the sustained disease control, absence of extrahepatic metastasis, and the patient's strong preference, laparoscopic liver resection was performed after obtaining informed consent. Pathological examination revealed adenocarcinoma consistent with metastatic breast cancer, with negative surgical margins. Postoperatively, endocrine therapy alone was continued, and the patient has remained recurrence-free for 3 years after liver resection.

CONCLUSIONS: This case represents a rare report of surgical resection for breast cancer liver metastasis after CDK4/6 inhibitor-based therapy. It suggests that local treatment may be effective even in cases with suspected endocrine-resistant disease and provides practical insight into patient selection and treatment strategies, as the case fulfilled previously reported criteria for local therapy.