Lung Cancer Staging

Staging is the process of finding out if cancer is localized or widespread. It will show if the cancer has spread to other body structures and, if so, how far. The treatment and prognosis (outlook for survival) for a patient with lung cancer depends, to a large extent, on the cancer's stage.

Staging of Non-Small Cell Lung Cancer (NSCLC)

The system most often used to describe the growth and spread of non-small cell lung cancer (NSCLC) is the TNM staging system, also known as the American Joint Committee on Cancer (AJCC) system. T stands for tumor (its size and how far it has spread within the lung and to nearby organs), N stands for spread to lymph nodes and M is for metastasis (spread to distant organs). In TNM staging, information about the tumor, lymph nodes, and metastasis is combined and a stage is assigned to specific TNM groupings. The grouped stages are described using Roman numerals from 0 to IV.

Non-small cell lung cancer T stages

Tis: Cancer is found only in the layer of cells lining the air passages. It has not invaded other lung tissues. This stage is also known as carcinoma in situ.

T1: The cancer is no larger than 3 centimeters (slightly less than 1 inches), has not spread to the visceral pleura (membranes that surround the lungs) and does not affect the main branches of the bronchi.

T2: The cancer has one or more of the following features:

• it is larger than 3 cm
• it involves a main bronchus, but is not closer than 2 cm (about inch) to the point where the trachea (windpipe) branches into the left and right main bronchi
• it has spread to the visceral pleura
• the cancer may partially clog the airways, but this has not caused the entire lung to collapse or develop pneumonia

T3: The cancer has one or more of the following features:

• it has spread to the chest wall, the diaphragm (breathing muscle that separates the chest from the abdomen), the mediastinal pleura (membranes surrounding the space between the two lungs), or parietal pericardium (membranes of the sac surrounding the heart).
• it involves a main bronchus and is closer than 2 cm (about inch) to the point where the trachea (windpipe) branches into the left and right main bronchi, but does not involve this area
• it has grown into the airways enough to cause one lung to entirely collapse or to cause pneumonia of the entire lung

T4: The cancer has one or more of the following features:

Non-small cell lung cancer N stages

N0: No spread to lymph nodes

N1: Spread to lymph nodes within the lung, hilar lymph nodes (located around the area where the bronchus enters the lung). Metastases affect lymph nodes only on the same sides as the cancerous lung.

N2: Spread to lymph nodes around the point where the windpipe branches into the left and right bronchi or to lymph nodes in the medistinum (space behind the chest bone and in front of the heart). Affected lymph nodes are on the same side of the cancerous lung.

N3: Spread to lymph nodes near the collarbone on either side, to hilar or mediastinal lymph nodes on the side opposite the cancerous lung.

Non-small cell lung cancer M stages

M0: No distant spread

M1: Distant spread is present. Sites considered distant include other lobes of the lungs, lymph nodes further than those mentioned in N stages, and other organs or tissues such as the liver, bones, or brain.

Stage grouping for non-small cell lung cancer

Once the T, N and M categories have been assigned, this information is combined (stage grouping) to assign an overall stage of 0, I, II, III or IV.  

 
Staging of Small Cell Lung Cancer

For small cell lung cancers, a two-stage system is most often used. These are "limited stage" and "extensive stage". Limited stage usually means that the cancer is only in one lung and in lymph nodes on the same side of the chest.

Spread of the cancer to the other lung, to lymph nodes on the other side of the chest, or to distant organs indicates extensive disease. Many doctors consider small cell lung cancer that has spread to the fluid around the lung to be an extensive stage.

Small cell lung cancer is staged in this way because it helps separate tumors that can be treated more effectively with radiation therapy from those which cannot. About two-thirds of the people with small cell lung cancer will have extensive disease when their cancer is first found.