Lung Cancer

Staging

As with all cancers, identifying the stage of lung cancer is essential for determining the prognosis and for treatment planning. Lung cancer is usually staged twice. First, your doctor will evaluate the results of your physical exam and imaging tests and assign a clinical stage. Then, after a staging procedure or surgical resection is done, a pathologist will examine tissue taken from the tumor and nearby lymph nodes and assign a pathologic stage, which provides more details about the cancer. The enhanced accuracy of the pathologic stage is key to determining the best treatment options and predicting the prognosis (outcome). Lung cancer is classified according to the tumor, node, metastasis (TNM) system developed by the American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (UICC); this system is based on data from around the world collected by the International Association for the Study of Lung Cancer (IASLC). Oncologists who evaluate the results of imaging studies and pathologists who examine lung tissue obtained by biopsy or surgery categorize the tumor according to its size and location (T), whether cancer cells are found in nearby lymph nodes (N) and whether cancer has spread to other parts of the body (M). Once a lung cancer has been classified with the TNM system, an overall stage is assigned to the cancer.

The TNM classification and the staging system for lung cancer were updated in 2009 by the IASLC, the UICC and the AJCC, and both non-small cell and small cell lung cancer are staged according to the updated system (Tables 1 and 2). You should talk with your doctor to make sure that your lung cancer is staged according to the updated system, as it can provide a more accurate prediction of outcome. In addition, the treatment options available to you may be different with the updated staging system.

Some doctors still define the stage of small cell cancer as either limited stage or extensive stage. With limited stage small cell lung cancer, cancer is found in only one lung and may also be found in lymph nodes in the chest and above the clavicle (collarbone) on either side. With extensive stage small cell lung cancer, cancer has spread to the other lung, to distant lymph nodes or to distant organs. Treatment is often selected according to these two stages, although the TNM classification provides more detailed prognostic information and is therefore a greater factor in decision-making.

Table 1. TNM Classification of Lung Cancer

Classification	Definition
Tumor (T)
Tx	Primary tumor cannot be assessed OR evidence of cancer according to laboratory studies, but no tumor seen on imaging studies or with bronchoscopy
T0	No evidence of primary tumor
Tis	Carcinoma in situ (in place)
T1 T1a T1b	Tumor is 3 cm (approximately 1 inch) or less in greatest dimension, surrounded by lung or visceral pleura (lining covering the outside of the lung), with no evidence of tumor in the main bronchus (airway) (See Figure 1) Tumor is 2 cm (approximately 3/4 inch) or less in greatest dimension Tumor is more than 2 cm in greatest dimension but not more than 3 cm in greatest dimension
T2 T2a T2b	Tumor is more than 3 cm but not more than 7 cm (approximately 2 3/4 inches); or tumor with any of the following features: Involves main bronchus, 2 cm or more distal to the carina (see Figure 2) Invades visceral pleura Associated with atelectasis (collapse of part of the lung) or obstructive pneumonitis (inflamma-tion of lung tissue) that extends to the hilar region but does not involve the entire lung Tumor is more than 3 cm but not more than 5 cm (approximately 2 inches) in greatest dimension Tumor is more than 5 cm but not more than 7 cm in greatest dimension
T3	Tumor is more than 7 cm or one that directly invades any of the following: chest wall, diaphragm, phrenic nerve, mediastinal pleura, parietal pericardium; or tumor in the main bronchus less than 2 cm distal to the carina but without involvement of the carina; or associated atelectasis or obstructive pneumonitis of the entire lung or separate tumor nodule(s) in the same lobe as the primary (see Figure 3)
T4	Tumor of any size that invades any of the following: mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, esophagus, vertebral body, carina OR presence of separate tumor nodule(s) in a different lobe of the lung with the primary tumor (see Figure 4)
Nodes (N)
Nx	Regional lymph nodes cannot be assessed
N0	No regional lymph node metastasis
N1	Cancer cells in peribronchial and/or hilar lymph nodes and intrapulmonary nodes on the same side as the lung with the primary tumor (see Figure 5)
N2	Cancer cells in mediastinal and/or subcarinal lymph nodes on the same side as the lung with the primary tumor (see Figure 6)
N3	Cancer cells in mediastinal or hilar lymph nodes on the same side as the lung with the primary tumor, OR in the scalene or supraclavicular lymph node(s) on the same or opposite side as the lung with the primary tumor (see Figure 7)
Metastasis (M)
M0	No distant metastasis
M1 M1a M1b	Distant metastasis Separate tumor nodule(s) in a lobe of the lung on the opposite side from the lung with the primary tumor; tumor with pleural nodules or malignant pleural or pericardial effusion (see Figure 8) Distant metastasis (see Figure 9)

Table 2: Stages of Lung Cancer

Stage	TNM Classification
Stage 0	Tis
Stage 1A	T1 (T1a or T1b), N0, M0
Stage 1B	T2a, N0, M0
Stage IIA	T1 (T1a or T1b), N1, M0 T2a, N1, M0 T2b, N0, M0
Stage IIB	T2b, N1, M0 T3, N0, M0
Stage IIIA	T1 (T1a or T1b), N2, M0 T2 (T2a or T2b), N2, M0 T3, N1 or N2, M0 T4, N0 or N1, M0
Stage IIIB	T4, N2, M0 Any T, N3, M0
Stage IVA	Any T, any N, M1a
Stage IVB	Any T, any N, M1b

Additional Sources of Information

Book: Staging Manual in Thoracic Oncology, available at www.iaslc.org
National Comprehensive Cancer Network: NCCN Guidelines for Patients: www.nccn.com
Non-small Cell Lung Cancer
Treatment Summaries: Lung Cancer