Mediastinal tumors can cause weight loss. Tumors are systemic diseases that may lead to loss of appetite, weight loss, and anemia. Mediastinal tumor is a common clinical chest disease, which is a tumor occurring in the sternum and spine, between the right and left mediastinal pleura, and is divided into primary mediastinal tumor and secondary mediastinal tumor. Secondary tumors are mostly secondary to lung cancer or tumors in other parts of the body. Some cases may have no obvious clinical symptoms. Some cases may have symptoms of esophageal compression, where the esophagus is compressed and dysphagia occurs affecting eating, which in turn may lead to emaciation. Some cases require radiotherapy, which may cause adverse effects such as loss of appetite and consequent weight loss. It is recommended that patients go to regular hospitals as soon as possible for early detection, diagnosis and treatment to avoid delays.