Abstract
BACKGROUND: Breast cancer is the most common malignancy and a leading cause of cancer-related deaths among women worldwide. Although treatment advances have improved outcomes, the 5-year survival rate for metastatic breast cancer remains low. Understanding the anatomical distribution, associated risks, and prognostic features of metastases in patients with newly diagnosed stage IV breast cancer is essential for improving clinical management. This study aims to comprehensively investigate these aspects using data from the SEER database. METHODS: This study utilized a retrospective cohort design, examining data from the Surveillance, Epidemiology, and End Results (SEER) database. The investigation considered patients diagnosed with stage IV breast cancer from SEER database. Using logistic regression, odds ratios (ORs) were calculated to determine the risk of various metastases, stratified based on sociodemographic and clinicopathological variables. Survival analyses were executed with Kaplan-Meier methodology in tandem with Cox regression analyses. RESULTS: Out of 356,789 breast cancer patients considered, 18,036 (5.06%) were diagnosed with de novo stage IV disease. Bone metastasis predominated with a composition ratio of 42.6%. Patients with the HR-/HER2+ subtype exhibited the highest metastasis incidence at the time of diagnosis, constituting 8.7% of the entire cohort. Male patients displayed heightened susceptibility to bone, lung, and brain metastases compared to female counterparts. Hispanic individuals exhibited the highest propensity for brain metastases. Relative to other subtypes, the HR-/HER2- patients were more inclined toward lung metastases. Those with bone metastasis had a median survival period of 27 months. Grade III patients with brain or liver metastases faced the most adverse prognoses. A comprehensive profile detailing metastasis patterns by demographics, tumor site and stage, biology, and treatment was presented. CONCLUSIONS: This study represents the most comprehensive analysis of metastasis' anatomical distribution and prognosis in breast cancer, offering invaluable insights into metastatic tendencies and characteristics.