There is no clinical statement about which one is more serious: pleural mesothelioma or lung cancer. It is recommended that those who are diagnosed with the disease should take active treatment. 1. Pleural mesothelioma: it is a rare pleural tumor and is mainly related to asbestos exposure and long-term exposure to radiation. Clinically, it is divided into diffuse malignant pleural mesothelioma, with relatively unsatisfactory prognosis, and limited pleural mesothelioma, mostly benign, with better prognosis. Typical symptoms of pleural mesothelioma patients include cough, chest pain, fever, dyspnea, anorexia, weight loss and pleural effusion. Clinical treatment for this disease includes surgery such as pleural total pneumonectomy and pleurodesis, as well as radiotherapy, chemotherapy and targeted therapy. 2. Lung cancer: a common disease in clinic, but the cause is still unclear, which may be related to long-term smoking, exposure to ionizing radiation, heredity and so on. The prognosis is relatively good for early stage lung cancer with active treatment. If lung cancer is in the middle or late stage and the cancer cells have metastasis, the prognosis is relatively poor. Typical symptoms of lung cancer patients include cough, chest pain, blood in sputum, dyspnea and hoarseness. Patients diagnosed with lung cancer can be treated with molecular targeted therapy, surgical resection of lesions, radiotherapy and interventional therapy. For those who are diagnosed with pleural mesothelioma or lung cancer, they should pay attention to adjusting their mentality and actively cooperate with doctors for treatment. Pay attention to daily rest and ensure balanced intake of nutrients.