A Systematic Review of Clinical Outcomes and Prognostic Factors for Patients Undergoing Surgery for Spinal Metastases Secondary to Breast Cancer

Abstract

Introduction Surgical treatment and cement augmentation procedures are effective palliative techniques for the treatment of symptomatic spinal metastases. However, clinical results specific to a breast cancer cohort are generally lacking. We aim to systematically review the literature for clinical outcomes following operative interventions and prognostic factors for the treatment of breast metastases to the spine. Specifically, we describe the survival and clinical outcomes of surgery and cement augmentation procedures for breast metastases to the spine and to determine prognostic variables that may help recognize which patients will perform better or worse following surgery. Methods We performed a literature review using PubMed to identify articles that reported outcomes and/or prognostic factors of the breast cancer patient population with spinal metastases treated with any surgical technique since 1990. Results A total of 19 surgical studies, 4 cement augmentation studies, and 6 nonsurgical prognostic variable studies met the preset inclusion criteria. All but three studies (two surgical and one cement augmentation) were retrospective in nature, and all studies were of level of evidence IV. Median postoperative survival for metastatic breast cancer was 21.7 months (8.2–36 months), mean rate of pain improvement was 92.9% (76–100%), mean rate of neurological improvement was 63.8% (53–100%), mean rate neurological decline was 4.1% (0–8%), and mean rate LTC was 92.6% (89–100%). Kyphoplasty studies reported a high rate of pain control in selected patients. Negative prognostic variables included: hormonal (estrogen and progesterone) and HER2 receptor refractory tumor status, high degree of axillary lymph node involvement, and short disease-free interval (DFI). All other clinical or prognostic parameters were of low or insufficient strength. Conclusion With respect to clinical outcomes, studies consistently found that surgery resulted in neurological improvement for a majority of patients, with a minimal risk of worsening, and kyphoplasty studies reported a high rate of pain control. Increased postoperative survival 2002 onwards was likely due to FDA approval of new chemotherapies. However, specific factors associated with shorter survival following surgery involve hormone and HER2 receptor status and disease-free interval.