Loco-Regional Treatment of the Primary Tumor in De Novo Metastatic Breast Cancer Patients Undergoing Front-Line Chemotherapy

SIMPLE SUMMARY: Approximately 8% of breast cancers are diagnosed with synchronous distant metastasis at initial diagnosis, a situation known as de novo metastatic disease. Despite advances in the systemic treatment of metastatic disease, the optimal management of de novo metastatic breast cancer has been a matter of debate over the past few decades. Several studies have investigated the role of loco-regional treatment of the primary tumor and whether it was associated with better oncological outcomes. However, the results of these trials have been highly heterogeneous and inconsistent, leaving this question unresolved. In this retrospective study, we aimed to investigate the characteristics, treatment, and long-term outcomes of a cohort of consecutive patients with de novo metastatic disease who received loco-regional treatment after front-line chemotherapy. The results of this analysis may help identify interesting differences among de novo metastatic breast cancer patients that could help clarify the management of this controversial subgroup of patients. ABSTRACT: Background: Loco-regional therapy (LRT) in de novo metastatic breast cancer (MBC) has been investigated in several clinical trials, with heterogeneous and conflicting results. Methods: We conducted a retrospective study of de novo MBC patients treated with front-line chemotherapy (FLC) followed by LRT of the primary tumor. Our aims were to evaluate the characteristics, treatment, and oncological outcomes in terms of progression-free survival (PFS), distant progression-free survival (DPFS), and overall survival (OS) of de novo MBC. We also investigated possible subgroups of patients with better outcomes according to menopausal status, biological sub-type, location, number of metastases, and radiologic complete response after FLC. Results: We included 61 patients in the study. After a median follow-up of 55 months, disease progression occurred in 60.7% of patients and 49.2% died. There were no significant differences in PFS, DPFS, and OS between different subgroups of de novo MBC patients. A trend toward better PFS and DPFS was observed in triple-positive tumors, without a statistically significant difference in OS. Conclusions: No specific subgroup of de novo MBC patients showed a statistically significant survival advantage after FLC followed by LRT of the primary tumor.