Stage 1a breast cancer with intraparenchymal embolus indicates the possibility of vascular and lymphatic metastases. When microscopic observation of surgically removed breast cancer specimens is performed, cancer cells are found in lymphatic vessels or blood vessels. Although metastasis may not necessarily occur through the lymphatic system or bloodstream, it still indicates that there is a greater possibility of metastasis. For patients with high-risk factors for intravascular cancer embolism in stage 1a surgery, postoperative radiotherapy and chemotherapy are generally recommended, which can reduce the chances of breast cancer recurrence in the later stage and greatly increase the treatment efficiency, which is beneficial to the patient’s condition.