What does this research mean for the field?

A combination of metastasis-directed SBRT and curative intent chemotherapy results in a median progression-free survival of 18.8 months in patients with bone-only oligometastatic breast cancer. Novelty: ClaimNovelty.NOVEL_FINDING. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

This research aims to evaluate the effectiveness of curative treatment combined with metastasis-directed therapy in patients with bone-only oligometastatic breast cancer.

February 19, 2026

Abstract PS1-09-04: A study of curative approach treatment along with metastasis-directed SBRT in bone-only oligometastatic breast cancer patients

Key Points

This research aims to evaluate the effectiveness of curative treatment combined with metastasis-directed therapy in patients with bone-only oligometastatic breast cancer.
Included patients with 1-5 bone-only metastases.
Administered SBRT to the metastatic site followed by chemotherapy (anthracycline and taxane).
Conducted surgical excision of the primary tumor after chemotherapy.
Evaluated response using PERCIST criteria.
Analyzed progression-free survival (PFS) and overall survival (OS) with multivariate analysis.
Median follow-up was 19.4 months with a median PFS of 18.8 months.
1-year PFS rate was 81.63%, and 2-year PFS was 71.43%.
92.4% local control at first follow-up; 97.9% complete metabolic response at last follow-up.
Median OS was 19.4 months with 1-year OS of 89% and 2-year OS of 74%.
96.4% showed reduced pain medication requirements following SBRT, with median time to pain response at 2.3 months.

Abstract

Abstract Purpose and Objectives: A combination of metastasis-directed ablative therapy and curative intent treatment for OMBC is an active area of research. We designed this prospective study to include a homogenous population of oligometastatic breast cancer patients with bone-only metastases. Materials and Methods: Patients with 1-5 bone only metastasis were included and received SBRT to the metastatic site followed by curative intent anthracycline and taxane based chemotherapy followed by surgical excision of the primary tumor. Patients with spinal metastasis received 30 Gy in 3 fractions over 3 days and non-spinal metastasis received 24Gy in 2 fractions over 2 days. Response assessment was done using PERCIST criteria. Results: Between June 2021 and April 2024, a total of 49 patients with a total of 84 metastatic sites were enrolled. After a median follow-up of 19.4 months (1.1-44.4 months), median PFS was 18.8 months (1.1-44.4 months) 95% CI 26.512-36.349, while the 1 and 2-year PFS were 81.63% and 71.43%, respectively. Local control at metastatic sites was 92.4% at first follow-up, and 97.9% had a complete metabolic response at last follow-up. Multivariate analysis for PFS showed patients who completed NACT (p-value: 0.05) and underwent surgical excision of the primary (p-value: 0.02) had significantly improved PFS, and hormone receptor positivity reached near significance (p-value: 0.07). Median OS for the entire cohort was 19.4 months (1.56-44.4 months), while the 1 and 2-year OS were 89% and 74%, respectively. Multivariate Analysis for OS revealed significantly improved OS for patients completing NACT (p-value:0.01), receiving LRRT (p-value:0.038), and presence of vertebral metastasis (p-value: 0.038). With SBRT, 96.4% of patients showed a decrease in pain medication step and requirement. The median time to pain response was 2.3 months (1.0-4.7 months). No Grade 3-4 toxicities were documented till last follow-up. Pain flare was the most common toxicity observed in 10.7% of the patients. Conclusion: Oligometastatic breast cancer is a very heterogeneous group of patients. Our study shows excellent outcomes in treatment-naïve, bone-only metastatic patients, emphasizing the need for patient selection. Citation Format: A. Dagar, A. Ghosh, A. Singhal, A. Amritt, J. Sharma, A. Kumar, A. Sharma, A. Batra, P. Patil, S. Saini, A. Mishra, S. Deo, A. Gogia, D. Sharma, S. Mallick. A study of curative approach treatment along with metastasis-directed SBRT in bone-only oligometastatic breast cancer patients 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 PS1-09-04.

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