Swelling below the umbilicus in late stage of squamous lung cancer may be related to tumor metastasis, ascites, intestinal paralysis and other reasons. 1. Tumor metastasis: if tumor cells are planted and metastasized to the peritoneum, swelling below the umbilicus can be caused due to the increase of tumor volume. 2. Ascites: Hypoproteinemia may occur in late stage of squamous lung cancer, which may lead to ascites, manifested as swelling below the umbilicus. 3. Intestinal paralysis: patients with advanced stage of squamous lung cancer may have hypokalemia due to poor feeding, leading to intestinal paralysis and decreased intestinal peristalsis, which increases gas in the intestinal tract and may be manifested as swelling below the umbilicus. It is recommended that people with advanced stage of lung squamous cancer swelling below the umbilicus go to the hospital in time to clarify the cause of the disease and carry out standardized treatment under the guidance of doctors.