Lung Cancer


Your doctor uses a process called staging to learn extensive information about your cancer diagnosis, such as the location of the tumor, its size, whether it has spread to lymph nodes or other organs, the existence of any biomarkers, and the type or subtype of the cancer. This information will help your doctor develop a prognosis (outlook) and design a treatment plan uniquely for you.

To gather this information, these and other tests may be used:

  • Physical exam.
  • Tests of blood, urine and body fluids.
  • Imaging studies. A positron emission tomography (PET), computed tomography (CT) of the chest and magnetic resonance imaging (MRI) of the brain are routine.
  • Tissue biopsy and/or liquid biopsy. Some biopsies are performed with a needle, although certain situations require that part or all of the tumor be removed surgically.
  • Biomarker and molecular testing to look for gene alterations and driver alterations.

The pathologist, a doctor trained in identifying diseases by studying cells and tissues under a microscope, will examine your biopsy sample and create a pathology report. It will include results of tissue sample testing and may include results from biomarker testing, tumor molecular analysis or other tests.

Staging usually occurs right after diagnosis, but the tests used for diagnosing and staging may be repeated during treatment to monitor the effectiveness of the treatment or to determine a recurrence. If the cancer returns, some of the original tests, including molecular tests, will be performed again. If a new stage is assigned, it is often preceded by an “r” to denote that it has been restaged and is different from the original stage given at diagnosis.

Lung Cancer Staging Systems

Developed by the American Joint Committee on Cancer (AJCC) and the International Association for the Study of Lung Cancer (IASLC), the AJCC TNM system uses the following categories to stage non-small lung cancer (NSCLC) (see Table 1): 

  • T category: identifies the primary tumor’s size and location. 
  • N category: indicates whether lymph nodes show evidence of cancer cells. This is important because it shows how far the disease has progressed. 
  • M category: describes distant metastasis (spread), if any. Cancer can grow into nearby tissue or travel through lymph vessels or blood vessels to more distant parts of the body. An M subcategory may be added based on the presence of tumor cells that can be detected only by using a microscope or molecular testing. 

First, the T, N and M status is reviewed to determine the extent of the cancer. Then, a number is assigned that can range from Stage 0 through Stage IV (see Table 2).

Stage 0 is also known as in situ, and it is a precursor of an invasive cancer. Stages I and II are generally confined to the local area where the cancer is found with or without adjacent lymph node involvement. They are treated as early stage and are considered potentially curable; therefore, every effort should be made to render a cure for these diagnoses. Stage III NSCLC is considered locally advanced, still confined to the chest but having spread to regional lymph nodes outside the lung in the mediastinum. Stage IV is locally or regionally advanced disease that has spread to distant sites, such as the other lung, brain, liver or bone. For illustration purposes, the tumors in the staging illustrations are only shown on one side of the lungs. They may, however, be present in any area of the lungs.

The Veterans Administration Lung Study Group (VALSG) staging system is commonly used to stage small cell lung cancer (SCLC), although the AJCC TNM system may also be consulted. VALSG divides SCLC into two stages:

Limited-stage SCLC is confined to one part of the chest, in just one part of the lung and in nearby lymph nodes. It is considered Stages I to III in the AJCC TNM staging system.

Extensive-stage SCLC has spread to other parts of the body, such as the area between the lungs, the other lung, or outside of the chest, such as to the brain or bone. It is considered to be Stage IV in the AJCC TNM staging system.

Table 1. AJCC System for Classifying of Lung Cancer

Category Definition
Tumor (T)
TX Primary tumor cannot be assessed, or tumor proven by the presence of malignant (cancerous) cells in sputum (mucus that has been coughed up) or bronchial washings (cells collected from inside the airways) but not visualized by imaging or bronchoscopy.
T0 No evidence of primary tumor.
Tis Carcinoma in situ.
Squamous cell carcinoma in situ (SCIS).
Adenocarcinoma in situ (AIS): adenocarcinoma with pure lepidic pattern (on the alveolar lining), ≯ (not more than) 3cm in greatest dimension.
T1 Tumor ≯ (not more than) 3 cm in greatest dimension, surrounded by lung or visceral pleura (membrane surrounding the lung), without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus).
T1mi Minimally invasive adenocarcinoma: adenocarcinoma (≯ [not more than] 3 cm in greatest dimension) with a predominantly lepidic pattern (on the alveolar lining) and ≯ (not more than) 5 mm invasion in greatest dimension.
T1a Tumor ≯ (not more than) 1 cm in greatest dimension.
T1b Tumor > (more than) 1 cm but ≯ (not more than) 2 cm in greatest dimension.
T1c Tumor > (more than) 2 cm but ≯ (not more than) 3 cm in greatest dimension.
T2 Tumor > (more than) 3 cm but ≯ (not more than) 5 cm or having any of the following features:
• Involves the main bronchus regardless of distance to the carina (ridge at the base of the trachea), but without involvement of the carina.
• Invades visceral pleura (membrane surrounding the lung).
• Associated with atelectasis (collapse of part of the lung) or obstructive pneumonitis (inflammation of lung tissues) that extends to the hilar region, involving part or all of the lung.
T2a Tumor > (more than) 3 cm but ≯ (not more than) 4 cm in greatest dimension.
T2b Tumor > (more than) 4 cm but ≯ (not more than) 5 cm in greatest dimension.
T3 Tumor > (more than) 5 cm but ≯ (not more than) 7 cm in greatest dimension or directly invading any of the following: parietal pleura (outer lung membrane), chest wall (including superior sulcus tumors), phrenic nerve (nerve that helps control breathing), parietal pericardium; or separate tumor nodule(s) in the same lobe as the primary.
T4 Tumor > (more than) 7 cm or tumor of any size invading one or more of the following: diaphragm, mediastinum (area between the lungs), heart, great vessels, trachea (windpipe), recurrent laryngeal nerve (nerve that helps speech), esophagus, vertebral body, or carina (at base of the trachea); separate tumor nodule(s) in an ipsilateral lobe (lobe that is on the same side of the body) different from that of the primary.
Node (N)
NX Regional lymph nodes cannot be assessed.
N0 No regional lymph node metastasis.
N1 Metastasis in ipsilateral (on the same side) peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension.
N2 Metastasis in ipsilateral (on the same side) mediastinal and/or subcarinal lymph node(s).
N3 Metastasis in contralateral (on the opposite side) mediastinal, contralateral hilar, ipsilateral (on the same side) or contralateral scalene, or supraclavicular lymph node(s) (located above the collarbone).
Metastasis (M)
M0 No distant metastasis.
M1 Distant metastasis.
M1a Separate tumor nodule(s) in a contralateral (on the opposite side) lobe; tumor with pleural or pericardial nodules or malignant pleural or pericardial effusion.
M1b Single extrathoracic (outside of the lung) metastasis in a single organ (including involvement of a single nonregional node).
M1c Multiple extrathoracic (outside of the lung) metastases in a single organ or in multiple organs.

Table 2. Stages of Lung Cancer

Stage TNM classifications
Occult carcinoma TX, N0, M0
0 Tis, N0, M0
IA1 T1mi, N0, M0
T1a, N0, M0
IA2 T1b, N0, M0
IA3 T1c, N0, M0
IB T2a, N0, M0
T2b, N0, M0
T1a or T1b or T1c, N1, M0
T2a or T2b, N1, M0
T3, N0, M0
T1a or T1b or T1c, N2, M0
T2a or T2b, N2, M0
T3, N1, M0
T4, N0 or N1, M0
T1a or T1b or T1c, N3, M0
T2a or T2b, N3, M0
T3, N2, M0
T4, N2, M0
T3, N3, M0
T4, N3, M0
Any T, Any N, M1
Any T, Any N, M1a or M1b
Any T, Any N, M1c
Used with permission of the American Joint Committee on Cancer (AJCC), Chicago, Illinois. The original and primary source for this information is the AJCC Cancer Staging Manual, Eighth Edition (2017) published by Springer Science+Business Media.