Clinical And Nonclinical Factors Associated With Confirmatory Biopsy In Metastatic Breast Cancer.

249Background: In patients with metastatic breast cancer, clinical practice guidelines include obtaining histologic confirmation of metastases when possible. The purpose of this study was to investigate patterns and correlates of receipt of a confirmatory biopsy. Methods: Data were abstracted from the records of patients diagnosed with metastatic breast cancer in the Michigan Breast Oncology Quality Initiative (MiBOQI), a statewide registry of 25 health systems. Patients with Stage IV disease at diagnosis were excluded. Analyses investigated associations between receipt of a confirmatory biopsy and disease, clinical and non-clinical factors, and treating health system. Results: Data were available for 1,231 (96%) of eligible patients between 2006 and 2015. Of these, 66% had a confirmatory biopsy; the proportion of patients having a biopsy varied between the 25 sites from 41% to 100% (p = 0.03). In bivariate analyses, younger age (p = 0.02), lower comorbidity (p = 0.007), longer time between the primary an...