A Prospective Study Assessing the Efficacy and Toxicity of Stereotactic Body Radiation Therapy for Oligometastatic Bone Metastases

Abstract

PurposeStereotactic body radiation therapy (SBRT) is a promising treatment for oligometastatic disease in bone due to its delivery of high dose to target tissue and minimal dose to surrounding tissue. The purpose of this study is to assess the efficacy and toxicity of this treatment in patients with previously unirradiated oligometastatic bony disease. Materials and MethodsIn this prospective phase II trial, patients with oligometastatic bone disease, defined as ≤3 active sites of disease, were treated with SBRT at XXXX between December 2016 and May 2019. SBRT dose and fractionation regimen were not protocol-mandated. Local progression-free survival (LPFS), progression-free survival (PFS), prostatic specific antigen (PSA) progression, and overall survival (OS) were reported. Treatment-related toxicity was also reported. ResultsA total of 98 patients and 126 lesions arising from various tumor histologies were included in this study. The median age of patients enrolled was 72.8 years (80.6% male, 19.4% female). Median follow-up was 26.7 months. The most common histology was prostate cancer (68.4%, 67/98). The most common dose prescriptions were 27/30 Gy in 3 fractions (27.0%, 34/126), 30 Gy in 5 fractions (16.7%, 21/126), or 30/35 Gy in 5 fractions (16.7%, 21/126). Multiple doses per treatment regimen reflect dose painting employing the lower dose to the clinical target volume (CTV) and higher dose to the gross tumor volume (GTV). Four patients (4.1%, 4/98) experienced local progression at one site for each patient (3.2%, 4/126). Among the entire cohort, 2-year LPFS (including death without local progression) was 84.8%, 2-year PFS (including deaths as well as local, distant, and PSA progression) was 47.5%, and 2-year OS was 87.3%. Twenty-six patients (26.5%, 26/98) developed treatment-related toxicities. ConclusionsOur study supports existing literature in showing that SBRT is effective and tolerable in patients with oligometastatic bone disease. Larger phase III trials are necessary and reasonable to determine long-term efficacy and toxicities.