Locally Ablative Therapies in Oligometastatic Breast Cancer

Area of Science:

• Oncology
• Surgical Oncology
• Breast Cancer Research

Background:

• Management of de novo metastatic breast cancer (dnMBC) often prioritizes palliation, leaving the survival impact of surgery or ablative therapies unclear, especially in oligometastatic disease.
• Oligometastatic dnMBC, defined by single-site metastases (brain, bone, liver, or lung), presents a unique challenge where local interventions might influence outcomes.

Purpose of the Study:

• To investigate the association between surgical and/or locally ablative treatments of primary and/or metastatic sites with overall survival (OS) in patients diagnosed with single-site oligometastatic dnMBC.
• To compare the OS of patients receiving no local ablative therapy (NLT) versus those undergoing primary breast tumor resection only (BR), metastatic site ablative therapy only (MT), or both (BR+MT).

Main Methods:

• A retrospective cohort study utilizing the National Cancer Database (2010-2020) identified patients with single-site oligometastatic dnMBC receiving systemic therapy.
• Patients were categorized into four groups: NLT, BR, MT, and BR+MT. Logistic regression identified factors associated with treatment strategy, and multivariable modeling estimated the association of treatment with OS.
• Data analysis was conducted between August 2024 and September 2025, focusing on overall survival as the primary outcome measure.

Main Results:

• The study included 22,433 patients; bone-only metastases were most frequent (68.8%). Locally ablative therapies were utilized in a minority of cases (BR+MT: 6.4%, MT: 10.6%, BR: 15.3%).
• Older age and higher comorbidity scores were associated with receiving NLT.
• Compared to NLT, primary breast tumor resection (BR) and combined therapy (BR+MT) were associated with improved OS (HR 0.62 and 0.60, respectively). Conversely, metastatic site therapy alone (MT) was linked to worse OS (HR 1.22).

Conclusions:

• Few patients with single-site dnMBC receive surgical or ablative therapy, despite potential survival benefits.
• Primary breast tumor resection, either alone (BR) or in combination with metastatic site therapy (BR+MT), is associated with improved overall survival in this patient population.
• For patients with single-site dnMBC considered for invasive interventions, resection of the primary breast tumor may offer a survival advantage.