Clinicopathological characteristics and survival outcomes in patients with synchronous lung metastases upon initial metastatic breast cancer diagnosis in Han population

Background We investigated the clinicopathological characteristics and survival of breast cancer lung metastases (BCLM) patients at initial diagnosis of metastatic breast cancer (MBC) in the Han population. Methods We attained clinical data of 3155 MBC patients initially diagnosed between April 2000 and September 2019 from the China National Cancer Center and finally included 2263 MBC patients in this study, among which 809 patients presented with lung metastases at first MBC diagnosis. The risk factors for BCLM were determined using multivariate logistic regression analysis and the prognostic factors of BCLM patients were assessed by univariate and multivariate Cox regression analyses. Results Patients with triple-negative subtype (42.3%) harbored the highest incidence proportions of lung metastases. Age ≥ 50 years, Eastern Cooperative Oncology Group (ECOG) 2, M1, hormone receptor-negative (HR-)/human epidermal growth factor receptor 2-positive (HER2) + subtype, triple-negative subtype and disease-free survival (DFS) > 2 years were remarkably associated with higher incidence of lung metastases, while invasive lobular carcinoma (ILC) and bone metastases were significantly correlated with lower odds of lung metastases at diagnosis. The median survival of BCLM patients was 41.7 months, with triple-negative subtype experiencing the worst prognosis of 26.8 months. ECOG 2, triple-negative subtype, liver metastases, multi-metastatic sites and DFS ≤ 2 years were significantly correlated with poor survival of BCLM patients. Conclusions Our study provides essential information on clinicopathological features and survival outcomes of BCLM patients at initial diagnosis of MBC in China.