On X-ray, central lung cancer is characterized by a deepening and enlargement of the hilar shadow and a mass in the hilar region. In addition, indirect signs, including limited emphysema, obstructive pneumonia and atelectasis, may be seen on X-ray. However, X-rays are often inaccurate in detecting central lung cancer. Therefore, when these signs appear, CT examination of the chest is usually needed, especially enhanced CT, which can clearly show the size and shape of the lung cancer mass, as well as the enlarged lymph nodes in the hilum and mediastinum. In addition, bronchoscopy is needed for central lung cancer, and biopsies should be taken and sent for pathological examination to clarify the specific pathological type to see whether it is squamous carcinoma, adenocarcinoma or small cell carcinoma.