125 Survival Analysis by Molecular Subtype for Surgically Treated Breast Cancer Spine Metastases

Abstract

INTRODUCTION: Breast cancer spine metastases are a devastating and pervasive clinical problem. Discoveries in tumor biology and the pathophysiology of metastatic disease have expanded systemic treatment options for metastatic breast cancer. The implications of evolving treatment strategies should inform the surgical treatment of spine metastases and the predicted prognosis to guide personalized approaches. METHODS: This is a multi-institutional, retrospective, observational cohort study of patients who underwent spine surgery for symptomatic breast cancer spine metastases from 2008-2020. We studied overall survival, stratified by breast cancer molecular subtype and calculated hazard ratios adjusting for demographics, tumor characteristics, treatments, and laboratory values. We tested the performance of established models (Tokuhashi, Bauer, SORG, NESMS) to predict and compare all-cause mortalities using time-dependent performance metrics. RESULTS: A total of 98 patients surgically treated for breast cancer spine metastases were identified. The 1-year probabilities of survival for HR+, HR+/HER2+, HER2+, and TNBC were 63%, 83%, 0%, and 12% (P <0.001). Postoperative chemotherapy and endocrine therapy were associated with prolonged survival. The SORG prognostic model had the highest discrimination. The performance of all prognostic scores improved when preoperative molecular data was considered in addition to postoperative systemic treatment data. CONCLUSIONS: Advanced HR+, HR+/HER2+ breast cancer portended significantly longer overall survival compared with HER2+ and TNBC tumors after surgery for symptomatic spine metastases. Hormone receptor status and postoperative systemic therapy should be considered in prediction models for a more accurate assessment of prognosis.