Single Arm Phase II Study of Fractionated Stereotatic Radiation Therapy (FSRT) for Bone Metastases in Breast Cancer

Inclusion criteria

• Diagnosis of invasive breast cancer
• Signed informed consent
• Bone metastases (confirmed by MRI within 4 weeks of enrollment).
• Paraosseous soft tissue ≤ 5cm. The tumour could involve the vertebral column, but did not have to, nor did it need to enter the spinal canal.
• KPS ≥ 40 or ECOG 0-2.
• The tumor is at least 2 mm away from the spinal cord. If the tumor is closer than 2 mm, surgical resection is required prior to FSRT or the total prescription dose of spinal cord is strictly limited.
• Failure of previous conventional external beam radiotherapy or surgery, residual tumor after surgery, medical inoperability, and refusal to undergo surgery.
• A maximum of three distinct noncontiguous spinal metastases per patient was allowed, and each of the separate sites may have involvement of 2 contiguous vertebral bodies.
• Patients have sufficient bone marrow reserve and liver and kidney function: neutrophil count ≥ 1500 cells / mm3; platelet count ≥ 70000 / mm3; hemoglobin (Hgb) ≥ 8.0 g / dl; if there is liver metastasis, AST and ALT \< 3x ULN
• The interval between systemic chemotherapy is more than 2 weeks, and the side effects recovery from previous treatment ≤ grade 1
• Patients receiving bisphosphonates, endocrine or targeted therapy at the same time were not included

Exclusion criteria

• Patients with mechanically unstable spine or epidural spinal cord compression were excluded; however, patients with previously documented spinal cord compression that had been decompressed and stabilized were eligible. Patients with \> 50% loss of vertebral body height were excluded.
• Patients in whom a delay in initiating treatment might have adversely affected neurological outcome.
• Patients with a pacemaker, unable to undergo MR imaging and unable to lie flat for at least 30 minutes.
• Patients who had a history of previous radiotherapy to the spine at the current level of interest.
• Patients who had received prior external-beam irradiation to the spine within 3 months of registration.
• Patients who had received systemic radiotherapy (Strontium-89) within 30 days of starting protocol treatment.
• Patients who had received chemotherapy within 2 weeks of starting protocol treatment.
• Patients who are unwilling or unable to receive regular follow-up.
• The patients judged by the researchers who could not be included in some special cases.
• Serious complications: cardiovascular disease, end-stage renal disease, serious liver disease, infection, et al.
• Pregnant women.