Stereotactic Body Radiotherapy for Bone Only Oligometastatic Breast Cancer: A Prospective Study

This is a prospective data collection of treatment outcome for newly diagnosed oligometastatic breast cancers with 1-3 bone metastases. Eligible patients will be identified from the weekly Breast MDC. Patients will receive the recommended systemic and local treatment (including metastases directed SBRT) according to our clinical practice guidelines.Patients will be followed according to our routine with clinical and radiologic assessment. It is preferred that the same imaging method that was used to originally detect the metastases be used in follow-up assessments. The first imaging for SBRT sites will be three months post SBRT and every three months for the first year, every 6 months for the second year, then annually. Response and progression for these metastases will be evaluated using the revised Response Evaluation Criteria in Solid Tumors (RECIST) guideline (version 1.1). Changes in the largest diameter (unidimensional measurement) of the tumor lesions is used in the RECIST criteria. If functional imaging (bone scan, PET) were used at staging, changes in the uptake will be used in follow up scans to determine response to treatment and progression. As for SBRT related morbidities, we will use the Common Terminology Criteria for Adverse Events (CTCAE v5) for toxicity reporting and scoring.