Objective：To investigate the expression of structural maintenance of chromosome 1A（SMC1A）in breast cancer，analyze its correlation with clinical pathologic features，and explore its influence on apoptosis of breast cancer cells. Methods：The study first analyzed the expression differences of SMC1A mRNA in breast cancer and healthy breast tissues and their prognostic significance using The Cancer Genome Atlas（TCGA）database. It then involved collecting tumor and adjacent non-tumor tissue samples from 48 breast cancer patients who underwent surgical resection at the First Affiliated Hospital of Nanjing Medical University from January to December 2023. Real -time quantitative polymerase chain reaction（RT - qPCR）and immunohistochemistry（IHC）were performed to analyze SMC1A expression and evaluate its correlation with clinical pathologic traits. Additionally，by downregulating SMC1A expression in the MCF - 7 breast cancer cell line，apoptosis - related protein changes were recorded. Results：Analysis of TCGA transcriptomic sequencing data revealed that SMC1A mRNA expression was significantly higher in breast cancer tissues compared to normal breast tissues，and was closely orrelated with poorer cancer prognosis. Clinical sample validation confirmed that SMC1A expression levels were significantly elevated in breast cancer tissues compared to adjacent tissues and were correlated with TNM stage， lymph node metastasis，and pathological differentiation. Downregulation of SMC1A via siRNA1 in MCF - 7 cells notably increased Cleaved - caspase - 3，Cleaved - caspase - 9，and Bax levels，while decreased Bcl2 levels. Conclusion：SMC1A is highly expressed in breast cancer tissues，correlating with disease progression and pathological differentiation. Early mechanistic investigations indicate that reducing SMC1A expression may promote apoptosis in breast cancer cells，suggesting its regulatory role could be critical in mitigating breast cancer progression.