Prognostic Factors and Their Impact on Survival in Patients with De Novo Metastatic Breast Cancer

This study aimed to investigate the prognostic factors affecting overall survival (OS) in patients with de novo metastatic breast cancer (dnMBC). Additionally, the importance of local treatments on survival was evaluated. The data of 106 patients with dnMBC were analyzed. Primary breast surgery was performed in 15 patients (14%), while first-line systemic therapy constituted the initial treatment modality for 91 patients (86%). Local treatments were administered to 48 patients (45%), of which 63% underwent breast surgery alone and 37% underwent both breast surgery and radiotherapy. In univariate analysis, patient performance status, extent of metastasis, response of primary breast tumors and metastatic lesions to first-line systemic therapy, administration of local treatments, and the use of breast radiotherapy and surgery were identified as prognostic factors (p< 0.050). In multivariate analysis, being in the triple-negative subgroup (HR: 5.06, 95% CI: 2.46–10.43, p< 0.001), having polymetastatic disease (HR: 1.19, 95% CI: 1.15–3.17, p= 0.013), partial response of metastatic lesions to first-line systemic therapy (HR: 2.25, 95% CI: 1.84–4.29, p= 0.014), and non-response to first-line systemic therapy (HR: 2.67, 95% CI: 1.56–4.59, p< 0.001) were identified as independent poor prognostic factors. The median OS was 34 months, with 2-year OS at 58% and 5-year OS at 19%. The most significant prognostic factors for dnMBC in this study were molecular subtyping, extent of metastasis, and response of metastatic lesions to first-line systemic therapy. Although local treatments targeting the breast influenced prognosis, their impact was not as strong as the aforementioned variables. Keywords: De novo metastatic breast cancer, Radiotherapy, Prognostic factors, Overall survival