In its earliest stages, lung cancer doesn’t typically cause symptoms, so most lung cancers are diagnosed when tumors have already grown and spread, and they begin to interfere with lung function. Sometimes lung cancer is detected earlier through a chest X-ray or other exam that doctors have ordered for reasons not related to the cancer—for example, a chest X-ray before a surgery.
Several tools are used to diagnose lung cancer. A doctor may order imaging tests, such as an endobronchial ultrasound, a chest X-ray, or a computed tomography (CT) scan.
To confirm the presence of lung cancer, doctors must perform a biopsy. This involves taking a sample of tissue and looking at the cells under a microscope. A number of methods can be used.
- In a bronchoscopy, a thin, lighted tube is inserted in the mouth or nose and down the windpipe into breathing passages. This allows doctors to see inside and also take a tissue sample. Navigational bronchoscopy is a technique that allows access to distant parts of the lung that cannot be reached using conventional bronchoscopy.
- In a needle aspiration, a needle is inserted through the chest wall into the tumor, usually under the guidance of CT imaging. The needle is used to withdraw cells.
- In a thoracentesis, a needle is used to remove fluid surrounding the lungs.
- In a thoracotomy, the chest is surgically opened so the surgeon can access the tumor.