How is lung cancer diagnosed?

You might have a number of tests to investigate your symptoms and confirm a diagnosis of lung cancer, including:^{[1],[2],[3],[4],[5],[6],[7]}

medical history and physical examination
imaging tests, such as chest X-ray, computed tomography (CT) scan, magnetic resonance imaging (MRI) scan,
nuclear medicine imaging, such as a positron emission tomography (PET) scan or bone scan. A weak radioactive substance is injected into the body to show the cancer in a clearer way. A bone scan can show cancer that has spread to the bones.
laboratory tests on blood or tissue
lung biopsy, where a small sample of tissue or fluid is removed, usually with a thin needle, to be examined under a microscope. This can be done percutaneously (through the skin) using imaging guidance, or through a bronchoscopy.
sputum cytology, where a sample of sputum (mucus coughed up from the lungs) is examined under a microscope
bronchoscopy, where a thin tube with a light and a lens on the end is inserted through the nose or mouth to look inside the trachea (windpipe) and large airways in the lungs, or to take biopsies
video-assisted thoracoscopy, where a thin tube with a light and a lens on the end is inserted into the chest (through a cut made between two ribs) to look for abnormalities, or to take biopsies
thoracentesis, where fluid is removed with a needle from the space between the lining of the chest and the lung, to be examined under a microscope
mediastinoscopy and mediastinotomy, where a thin tube with a light and a lens on the end is inserted into the area between the lungs (through a cut in the front of the neck or between two ribs) to look for abnormalities, or to take biopsies.

Staging

If you are diagnosed with lung cancer, you might have more tests to determine the stage of the disease and whether the cancer has spread to other parts of the body. Knowing the stage of the disease helps your medical team plan the best treatment for you.

Non–small cell lung cancer is divided into 6 stages, depending on whether the cancer has spread to other areas of the body:^{[8],[9],[10],[11],[12]}

Occult (hidden) stage – cancer cells are found in sputum or other fluids from the lung, but the cancer is not seen in other tests.
Stage 0 (carcinoma in situ) – the cancer is in the top layers of cells lining the air passages. It has not spread to lymph nodes or distant areas of the body.
tags I (divided into IA and IB), II (divided into IIA and IIB) and III (divided into IIIA, IIIB and IIIC) – these involve the cancer increasing in size, and spreading to nearby lymph nodes (stages II and III).
Stage IV (divided into IVA and IVB)– the cancer may have spread to the opposite lung, space around the lungs or heart, or other organs, such as bone, liver and brain.

Small cell lung cancer is divided into 2 stages for the purposes of treatment:^[13]

Limited stage – the cancer is in only 1 side of the chest (possibly including lymph nodes) and can be treated with a single radiation field.
Extensive stage – the cancer has spread widely throughout the lung, to the other lung, to lymph nodes on the other side of the chest or to distant organs.

The staging system used for non–small cell lung cancer is increasingly being used for small cell lung cancer.

Tests to determine the stage of lung cancer can include:^{[14],[15],[16],[17]}