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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 1¼ 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 ¾ 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 ¾ 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:
- it has spread to the mediastinum (space behind the chest bone and in front of the heart), the heart, the trachea
(windpipe), the esophagus (tube connecting the throat to the stomach), the backbone or the point where the windpipe branches into the left and right
main bronchi
- two or more separate tumor nodules are present in the same lobe
- there is a malignant pleural effusion (fluid containing cancer cells in the space surrounding the lung)
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. |
