Establishing the Prevalence of Complicated Bone Metastases in Community Radiation Oncology Clinics

Abstract

Numerous randomized trials have established the noninferiority of single-fraction radiation therapy (RT) to multi-fraction RT for palliation of painful bone metastases. Yet most used complicating features as exclusion criteria, and a clear definition and understanding of the prevalence of such features is lacking, particularly in community settings. To further characterize this prevalence outside of a tertiary-care setting, we performed a retrospective review of community-treated patients. A retrospective review of the electronic medical record was performed for patients treated with palliative RT to symptomatic bone sites between 5/2013 and 5/2016 in two community hospital-based radiation oncology clinics. Baseline demographic, disease, and treatment data were collected as well as the presence of potential complicating features including history of prior RT, prior surgery, pathologic fracture, and neuraxis compromise at the RT treatment site. Descriptive statistics summarized rates of complicating features. Two-sample tests of proportions quantified the difference (diff) in rates of complicating features between the present population vs. published rates from a tertiary-care center. Cox regressions were performed to determine the effect of complicating features on survival. Among 182 patients, 216 bone sites were treated. Median age was 68.9 years (range 25-94), 54.9% of patients were male, 73.6% were white, 17% were black, and 9.3% were another race. Median time from initial cancer diagnosis to RT consult was 14 months (standard deviation 47). The most common histology was breast (26%), followed by lung (23%), prostate (21%), hematologic malignancies (2%), and other histologies (28%). Symptomatic sites were spine (54%), hip/pelvis (16%), extremity (15%), chest wall (12%), and skull (4%). Among all patients, 54.2% had at least one complicating feature. Percent of target sites complicated by prior RT was 2.8% (diff: -.016, p = .30), prior surgery 10.2% (diff: .013, p = .56), pathologic fracture 31.5% (diff: .109, p = .0009), and soft tissue component 35% (diff: -.036, p = .34). Among 151 spine and medial pelvis sites, there was evidence of neuraxis compromise in 51% of cases (diff: -.01, p = .83). Prior surgery was associated with longer survival time (HR: .56; p = .031), but no other complicating features demonstrated a significant effect on survival. Complicating features of bone metastases are common and occur at similar rates in both tertiary-care and community hospital-based radiation oncology clinics. Aside from prior surgery at the RT site, there were no additional associations between complicating features and survival time in this population. Given the high prevalence of complicating features, these results support the need for future studies aimed at characterizing optimal management for complicated bone metastases.