Clinicopathological discordance and survival outcomes in 154 breast cancer patients with pulmonary metastasis in a real-world setting

PURPOSE: This study aimed to investigate the clinicopathological significance of pulmonary metastasis in breast cancer patients and to evaluate the prognostic outcomes of lung metastasis subtypes. METHODS: A retrospective analysis was conducted on breast cancer patients who underwent lung nodule biopsy at Peking University Cancer Hospital between 2010 and 2024. We identified 180 biopsied patients. Analyses of receptor discordance and survival were performed in the 154 pulmonary metastasis cases and primary lung cancers were described only for differential diagnosis. RESULTS: Among 2,857 breast cancer patients with lung nodules, 180 (6.3%) underwent pathological confirmation, including 154 (85.6%) with breast cancer lung metastases and 26 (14.4%) with primary lung cancers. In 128 patients with complete receptor profiles, the overall discordance rate between primary and metastatic lesions was 18.0% (95% CI, 11.2-24.7). The discordance rates for ER, PR, and HER2 were 10.9%, 26.6%, and 10.9%, respectively. Based on metastatic receptor status, 73 (47.4%) patients were classified as HR+/HER2-, 44 (28.6%) as HER2+, and 37 (24.0%) as triple-negative, with 3-year overall survival rates of 95.9%, 94.1%, and 65.3%, respectively (P < 0.001). CONCLUSION: Lung biopsy is indispensable for reassessing receptor status to guide systemic therapy and for differentiating metastatic lesions from primary lung cancers. Receptor heterogeneity between primary and metastatic sites was observed, and survival outcomes varied across lung metastasis subtypes.