When a lung cancer patient develops swollen feet, the following two possibilities should generally be considered: First, lung cancer can cause great depletion of the body, which can lead to hypoproteinemia. When the protein in the body is low, it can cause edema, including swelling of the feet and generalized edema. Second, lung cancer can also cause multiple metastases, and when lymphatic tract metastasis occurs, it can affect the obstruction of lymphatic flow. This can cause swelling of both lower extremities and also upper extremities. Therefore, the appearance of swollen feet in lung cancer often indicates that lung cancer is in advanced stage. It should be clarified by timely improvement of corresponding examinations, such as liver and kidney function, as well as whole body bone scan and PET-CT.