In the assessment of lung cancer, computed tomography guides the use of bronchoscopy and establishes whether local treatment may be appropriate for the NSCLC or whether it is at an advanced stage. Percutaneous biopsy of a lesion suspected to be a metastasis can provide histological confirmation, allowing staging to be carried out at the same time. The initial presentation depends on the staging and histological type, ranging from an isolated nodule or mass to atelectasis or obstructive pneumonia, isolated lymph node disease or isolated pleural effusion to miliary metastasis in tumors showing EGFR mutation. Tumor (T) status depends on tumor size, distance from the carina, and invasion of the chest wall and mediastinal organs. PET-CT is superior to CT in identifying lymph node invasion (N2 for ipsilateral mediastinal disease and N3 for contralateral or supraclavicular disease). As a general rule, all contraindications for surgery should be confirmed via histological examination, with the exception of cerebral metastases.