We examined the relationship between SDC1 expression (in tumor and stromal cells) and patient OS and event-free survival (EFS) using a multivariable Cox regression model, adjusting for clinically significant variables including age, tumor characteristics, nodal involvement, menstruation status, radiotherapy, chemotherapy, vascular invasion, and TNM stage across different molecular subtypes: Luminal, HER2 + , and triple-negative breast cancer. The gene discussed is ERBB2; the disease is triple-negative breast carcinoma.