Prognostic factors and survival of patients undergoing surgical intervention for breast cancer bone metastases

INTRODUCTION: Bone is the most common distant site of breast cancer metastasis. Skeletal lesions can cause significant morbidity due to pain, pathologic fracture, and electrolyte abnormalities. Current treatment for patients with bone metastases (BoM) from breast cancer is highly personalized and often involves a multidisciplinary approach with chemotherapy, hormone therapy, bone-targeted antiresorptive agents, radiation therapy, and surgery. We have retrospectively collected clinical data from a series of patients with bone metastases to evaluate the clinical characteristics, prognostic factors, and survival patterns of patients with breast cancer BoM receiving standard multimodal therapy. METHODS: A consecutive series of 167 patients with breast cancer BoM treated at a single institution between August 2013 and March 2020 were identified. Clinical information was obtained from the medical record and survival analyses were performed to evaluate patient outcomes and identify prognostic factors. RESULTS: Thirty-seven patients (22%) presented with de novo BoM – bone metastases at the time of breast cancer diagnosis – and were 2.6 times more likely to die within the study period than those with asynchronous BoM (HR = 2.62, p = <0.0001). Patients who received bone-targeted medical therapy were 61% less likely to die after BoM diagnosis than those who did not (HR = 0.39, p = 0.001). Operative stabilization of BoM was more frequently employed in patients with lytic (p = 0.02) or mixed (p = 0.02) tumors than it was for those with blastic lesions. Patients treated with surgery had a lower overall bone metastasis survival than those treated without (p < 0.03). DISCUSSION: These findings reflect the current patterns in metastatic breast cancer treatment and associated outcomes. In a series of 167 consecutive patients, we demonstrate the natural history of breast cancer with BoM being treated with modern multimodal therapy. Understanding these treatment patterns and prognostic factors enhances the provider’s ability to counsel patients and direct appropriate treatments.