Clinicopathological characteristics, prognosis, and therapeutic implications in breast cancer with pathologically confirmed bone marrow metastases: an observational retrospective study

Abstract Objectives The factors associated with bone marrow metastasis (BMM) in breast cancer (BC) remain poorly understood. This study aimed to investigate the clinicopathological characteristics, prognosis, and therapeutic implications of BC with BMM. Methods This study included patients with BC who underwent bone marrow biopsy for suspected BMM at The First Hospital of Jilin University between January 2010 and August 2018. Patients were classified into BMM and non-BMM groups based on biopsy results. The primary outcome was overall survival (OS), assessed using the Kaplan–Meier method and analyzed with Cox regression. Results Of the 106 patients evaluated, 70 had confirmed BMM. All patients with BMM exhibited bone metastases, with the majority (90 %) displaying bone as the initial site of distant metastasis. A significant association was found between BMM and an increased number of metastatic sites (p=0.004). The median OS after bone marrow biopsy was 5.93 months for BMM patients and 10.63 months for non-BMM patients (p=0.429). Cox regression analysis showed that patients continuing systemic therapy had a markedly longer median OS (11 vs. 2.07 months, p<0.001). Chemotherapy yielded a higher survival benefit compared to other agents (12.23 vs. 3.13 months, p=0.001), and the effectiveness of combination chemotherapy surpassed that of mono-chemotherapy (median OS 15.93 vs. 5.8 months, p=0.049). Conclusions BC with BMM is characterized by concurrent bone metastases and a higher number of metastatic sites. Although BMM is associated with a poorer prognosis, systemic therapy, particularly combined chemotherapy, significantly enhances survival outcomes.