The leg swelling of rectal cancer patients may be caused by general malnutrition, because patients have tumor in rectum and the malignancy of tumor is very high, many tumor patients will have nutritional disorder, which is manifested as lower albumin, so it will cause general edema. At first, the edema is mainly in the lower limbs, manifested as leg swelling, and then gradually spread upward from the ankles, even leading to edema in the whole lower limbs, so it is necessary to increase nutrition and supplement albumin level when necessary. It is also possible that patients with rectal cancer are combined with some medical diseases, such as hypertension, coronary heart disease and chronic kidney disease, which may lead to leg swelling, and if necessary, they should go to a specialist for examination. In addition, if the tumor is very advanced and pelvic metastasis occurs, some important blood vessels in the lower limbs will be compressed, resulting in obstruction of venous and lymphatic return, and the patient will also have swollen legs.