Abstract PS1-08-16: Local interventions in oligometastatic breast cancer: systematic review and meta-analysis

Abstract Introduction: Breast cancer is the most common neoplasm among women worldwide. It is estimated that, in the 2023-2025 period, around 22,000 women will develop metastases, of which approximately 20% will have oligometastases. Some evidence suggests that local treatment with radiotherapy or surgery may prolong survival. However, the benefits of this approach are still not fully clear. Objective: To evaluate the effectiveness of local therapies, such as radiotherapy and surgery in combination with systemic therapy in the treatment of patients with oligometastatic breast cancer. Method: A systematic review was carried out with registration in the PROSPERO database (CRD42024525782), Medline via Ovid, EMBASE, Web of Science, Cochrane Library Databases, Scopus and Clinical Trials, until November 2024. RCTs were selected, involving women with oligometastatic breast cancer in systemic treatment associated with intervention, radiotherapy or surgery, compared to standard systemic treatment. The processes of study selection, data extraction, risk of bias analysis and level of evidence were carried out by independent and blind authors. For this, platforms such as Rayyan and a standardized Excel form were used. The methodological quality was analyzed by ROB-2 and the evidence was assessed with GRADE. For quantitative data analysis, the Review Manager - RevMan program (version 5.3) was used. Results: Among 717 studies, 2 randomized controlled trials were included in this review. When comparing the association of radiotherapy or surgery with systemic therapy, overall survival presents RR: 1.78 (CI: 0.26 - 12.17), 162 participants, high risk of bias, very low quality of evidence. For progression-free survival in this same comparison RR: 1.05 (CI: 0.76 - 1.46) 162 participants, high risk of bias, very low quality of evidence. Finally, in this same comparison for the secondary outcome, adverse effects, it was analyzed by subgroups, Grade 3 RR: 1.06 (CI: 0.52 - 2.13) 162 participants, high risk of bias, very low quality of evidence and the subgroup Grade 4 RR:0.42 (CI: 0.10 - 1.80) 162 participants, high risk of bias, very low quality of evidence. Conclusion: There are no benefits from the association of systemic therapy with radiotherapy or surgery in oligomestases compared to systemic therapy for the outcomes of overall survival, disease progression-free survival and adverse events. Citation Format: C. Molina, A. Dalama, D. Silva, G. Tosello, M. Cruz, A. Toledo. Local interventions in oligometastatic breast cancer: systematic review and meta-analysis [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS1-08-16.