The precautions to be taken before breast cancer surgery are fasting and abstaining from food and drink, ensuring enough rest, regulating mood, and conducting preoperative examination. 1. Fasting and drinking: patients should avoid eating 12 hours before breast cancer surgery, and should not drink water 4 hours before surgery. This can prevent the patient from aspiration of vomit or choking during surgery. 2. Ensure enough rest: breast cancer patients should develop regular sleeping habits before surgery, avoid staying up late, ensure enough rest, and should not overwork or do strenuous exercise. 3. Regulate the mood: breast cancer patients should keep their mood relaxed and avoid excessive anxiety and tension before surgery. 4. Conduct preoperative examination: breast cancer patients also need to undergo coagulation index, blood routine biochemistry, infectious disease screening, tumor markers, breast ultrasound, liver ultrasound, lung function and other examinations before surgery. It is suggested that breast cancer patients need to wear loose clothes before surgery, and also need to clean the skin around the armpit and breast at the operation site.