Staging in Depth
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Staging and T, N, M Categories
Three key factors are used to determine the cancer stage: T (the size of the tumor), N (if the lymph nodes are involved in the cancer) and M (if the cancer has metastasized, or spread, to other organs in the body).
T Categories
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TX
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Cancer cells were found from a sputum cytology but a tumor cannot be seen with imaging tests.
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T0:
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No evidence of a primary tumor.
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Tis
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Cancer is only in the top layers of cells lining the air passages and is not found in deeper lung tissue. This is also known as carcinoma in situ.
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T1:
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Tumor is not larger than three centimeters wide. Cancer is not in the pleura or in the main bronchi.
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T1a
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Tumor is 2 centimeters (cm) or less
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T1b
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Tumor is 2 to 3 cm
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T2
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The tumor is more than 3 cm but less than 7 cm, or involves one or more of the following:
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T2a
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Tumor more than 3 cm but less than 5 cm
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T2b
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Tumor more than 5 cm but less than 7 cm
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Cancer involves a main bronchus but is not closer than two centimeters to the area where the trachea splits to enter each lung (the carina).
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Cancer invades pleura surrounding lung.
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Partial, but not total collapse of lung, from tumor involvement
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T3
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Tumor is more than 7 cm or involves one or more of the following:
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Cancer invades the chest wall, diaphragm, pleura or the sac around the heart.
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Cancer involves a main bronchus and is closer than two centimeters to the carina.
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Tumor causes a total lung collapse or pneumonia.
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Multiple tumor masses in the same lobe of the lung
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T4
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Cancer involves one or more of the following:
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Tumor (any size) invades the trachea, esophagus, carina, mediastinum (the area in front of the heart and behind the chest bone), heart, a large blood vessel near the heart, or the spine or backbone.
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Additional lung cancer mass in a different lobe but on the same side as the main tumor
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N Categories
| NX |
Regional (nearby) lymph nodes cannot be evaluated. |
| N0 |
Cancer has not spread to regional lymph nodes. |
| N1 |
Cancer has spread to lymph nodes in or around the lung (on the same side as the tumor). |
| N2 |
Cancer has spread to lymph nodes near the carina or in the mediastinum (on the same side as the tumor). |
| N3 |
Cancer has spread to same-side or opposite-side lymph nodes near the collar bone or to opposite-side lymph nodes near the mediastinum or hilum (where the bronchus and vessels enter the lung). |
M Categories
| MX |
Distant metastases (cancer spread) cannot be evaluated. |
| M0 |
No distant metastases found. |
| M1 |
Cancer has spread to one or more distant organs or regions. |
| M1a |
Separate tumor mass in a lobe on the opposite side, tumor spread to the pleura, or malignant cells in pleural or pericardial fluid. |
| M1b |
Distant metastases (extra-thoracic) |
Overall Staging for Non-Small Cell Lung Cancer
Once the T, N and M categories are determined, the information is combined and used to decide the overall cancer stage. Overall staging for non-small cell lung cancer (NSCLC) is characterized by Stage I through Stage IV. The lower the staging number, the less advanced the cancer.
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Stage
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TNM
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What It Means
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Occult Stage
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TX, N0, M0
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Cancer cells are found in the sputum or in the sample of cells collected during a bronchoscopy but a tumor is not seen in the lung.
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Stage 0
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Tis, N0, M0
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Cancer cells are found in only a few layers of cells and have not grown beyond the lung's inner lining. A Stage 0 tumor is called carcinoma in situ.
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Stage IA
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T1a, N0, M0
T1b, N0, M0
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All Stage I lung cancers are contained within the lung and cancer cells are not found in the lymph nodes. In Stage IA, the tumor is invasive and has grown through the inner lining into the deeper tissue of the lung. The tumor does not exceed three centimeters. Tissue surrounding the tumor is normal.
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Stage IB
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T2a, N0, M0
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Tumor is larger than three centimeters but less than 5 cm and has grown deeper. It may have grown into the bronchus or through the lung into the pleura. Cancer is not in the lymph nodes.
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Stage IIA
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T1a, N1, M0
T1b, N1, M0
T2a, N1, M0
T2b, N0, M0
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Tumor is less than 5 cm and cancer cells may be in nearby lymph nodes. The tumor has not invaded the bronchus and it has not spread to other areas of the body.
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Stage IIB
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T2b, N1, M0
T3, N0, M0
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The cancer is 5 to7 cm and involves hilar lymph nodes, or invades surrounding structures, or has other masses in the same lobe.
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Stage IIIA
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T1-3, N2, M0
T3, N1, M0
T4, N0-1, M0
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Cancer cells are found in same side mediastinal lymph nodes. An additional lung mass in another lobe on the same side. The tumor can be any size.
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Stage IIIB
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Any T, N3, M0
T4, N2, M0
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Cancer cells are found in lymph nodes in the neck or on the other side of the chest from where the tumor is located. Cancer is quite extensive to surrounding structures. The tumor can be any size. An additional lung mass in another lobe on the same side.
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