Sudden foot swelling three months after tumor surgery is considered to be possibly caused by malnutrition, cardiogenic edema, and impaired lymphatic fluid and blood return. 1. malnutrition: after major surgeries such as tumor surgery, patients may suffer from insufficient nutritional intake, which decreases the protein level in the body, thus causing swelling of feet and lower limbs, and need to be supplemented with nutrients or given nutrient solution for treatment in time. 2. cardiogenic edema: after tumor surgery, it may cause cardiac excretion dysfunction, which increases the pressure of the venous system as well as decreases the output of cardiac blood, causing retention of body fluids, and ultimately causing generalized or limited edema and swelling of the feet. 3. Obstruction of lymphatic fluid return: patients who do not get the proper amount of exercise and stay in bed after surgery, resulting in low lymphatic fluid return function, will show localized swelling, such as feet, lower limbs and so on. After tumor surgery, patients should pay attention to avoid overwork, keep happy mood, and make clear treatment under professional doctor’s guidance, pay attention to dietary habits and ensure balanced nutrition, which are all of positive significance for postoperative recovery.