Survival Analysis of Breast Cancer Subtypes in Patients With Spinal Metastases

Study design We conducted a retrospective cohort study of 151 patients with breast cancer spinal metastases. Objective To investigate the influence of breast cancer subtypes on survival duration of patients with breast cancer spinal metastases, and to aid spine surgeons in selecting treatments on a more precise basis. Summary of background data There is lack of knowledge about specific prognosis of patients with spinal metastases in various breast cancer subtypes. Estrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor 2 (Her-2) status are the key factors in determining breast cancer subtypes and predicting patients' response to adjuvant treatments. Methods Until August 2013, we retrieved 151 surgically treated patients with breast cancer spinal metastases and followed up all the patients for at least 2 years. Survival duration analysis and Cox proportional hazards regression model unadjusted and adjusted by age were used. Results Patients with ER-negative (-) breast cancer had 11 months shorter median survival duration (10.6 vs. 21.5 mo) and 48% higher mortality risk (P=0.03) than those with ER-positive (+) breast cancer. Patients with PgR (-) status had 59% higher mortality risk than those with PgR (+) status (P=0.02). Hormone receptor (HR) status is a combination of ER and PgR status. Patients with HR (-) status had an 11-month shorter median survival duration and 52% higher mortality risk (P=0.01) than patients with HR (+) status. Human epidermal growth factor receptor 2 subtypes had similar median survival duration and mortality risk. Patients with triple-negative breast cancer had a median survival duration of only 9.9 months. Conclusion Patients with spinal metastases with ER/HR (-) status and triple-negative breast cancer could be downgraded from score "5" to "3" in Tokuhashi scoring system and from "slow growth" to "moderate growth" in Tomita scoring system. Spine surgeons should be critical before performing high-risk extensive surgery in patients with ER/HR (-) status, and especially, in those with triple-negative status. Level of evidence 3.