Local control of 1-5 fraction radiotherapy regimens for spinal metastases: an analysis of the impacts of biologically effective dose and primary histology

• Authors: Roman O Kowalchuk, Mayo Clinic, Rochester; David Cousins, University of Virginia; Kelly M Spencer, University of Virginia; Martin K Richardson, University of Virginia; James M Larner, University of Virginia; Timothy N Showalter, University of Virginia; Wiliam H Mcallister, Riverside Regional Medical Center; Jason P Sheehan, University of Virginia; Ronald C Kersh, University of Virginia; Sunil Dutta, Emory University
• Journal Title: Reports of Practical Oncology and Radiotherapy
• Volume: Volume 26, Number 6
• Publisher: via Medica Journals | 2021-01-01, Pages 883-891
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.5603/RPOR.a2021.0099
• Subjects: Health Sciences, Oncology; Biology, Radiation
• Keywords: dose-escalation; metastasis; palliative care; spine; stereotactic body radiation therapy (SBRT)

Abstract

background: This analysis evaluates the impacts of biologically effective dose (BeD) and histology on local control (Lc) of spinal metastases treated with highly conformal radiotherapy to moderately-escalated doses. Materials and methods: Patients were treated at two institutions from 2010-2020. Treatments with less than 5 Gy per fraction or 8 Gy in 1 fraction were excluded. The dataset was divided into three rpa classes predictive of survival (1). The primary endpoint was Lc. results: 223 patients with 248 treatments met inclusion criteria. patients had a median Karnofsky performance status (Kps) of 80, and common histologies included breast (29.4%), non-small cell lung cancer (15.7%), and prostate (13.3%). a median 24 Gy was delivered in 3 fractions (BeD: 38.4 Gy) to a median planning target volume (pTV) of 37.3 cc. 2-year Lc was 75.7%, and 2-year Os was 42.1%. Increased BeD was predictive of improved Lc for primary prostate cancer (hr = 0.85, 95% cI: 0.74-0.99). Patients with favorable survival (RPA class 1) had improved LC with BED > 40 Gy (p = 0.05), unlike the intermediate and poor survival groups. No grade 3-5 toxicities were reported. conclusions: Moderately-escalated treatments were efficacious and well-tolerated. BeD > 40 Gy may improve Lc, particularly for prostate cancer and patients with favorable survival.