A large analysis of 270,564 breast cancer surgery patients found postoperative venous thromboembolism occurred in 0.2% of cases. Risk rose with older age, higher BMI, heart failure, metastatic disease, low albumin, longer operations, and more extensive surgery. The dataset quantifies a low absolute event rate while identifying a recognizable high-risk profile that could guide thromboprophylaxis decisions and postoperative monitoring. It also provides evidence for risk-factor stratification rather than one-size-fits-all approaches. For perioperative teams, the operational implication is refining patient selection for interventions that prevent rare but serious complications.