Oligometastatic breast cancer treated with curative-intent stereotactic body radiation therapy

Purpose Prospective pilot study to assess patient outcome after stereotactic body radiation therapy (SBRT) for limited metastases from breast cancer. Methods Forty patients with ≤5 metastatic lesions received curative-intent SBRT, while 11 patients with >5 lesions, undergoing SBRT to ≤5 metastatic lesions, were treated with palliative-intent. Results Among those treated with curative-intent, 4-year actuarial outcomes were: overall survival of 59%, progression-free survival of 38% and lesion local control of 89%. On univariate analyses, 1 metastatic lesion (versus 2–5), smaller tumor volume, bone-only disease, and stable or regressing lesions prior to SBRT were associated with more favorable outcome. Patients treated with palliative-intent SBRT were spared morbidity and mortality from progression of treated lesions, though all developed further metastatic progression shortly (median 4 months) after enrollment. Conclusions SBRT may yield prolonged survival and perhaps cure in select patients with limited metastases. Palliative-intent SBRT may be warranted for symptomatic or potentially symptomatic metastases.