Non-Small Cell Lung Cancer - Staging Systems

Highlights	Diagnostic Tests	Chemotherapy Treatments
Introduction	Complications	Investigative Agents
Causes	Staging Systems	Resources
Symptoms	Treatment Options by Stages	References
Risk Factors	Surgical Procedures
Lifestyle Changes	Radiation Treatments

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Staging Systems

Tests to Determine Cancer Stage. Once a diagnosis of non-small cell lung cancer has been made, the physician makes treatment choices by determining the cancer's stage (how large the tumor is and how far the cancer has spread). To stage the cancer and determine other aspects of the disease, a number of tests are conducted:

The cancer cells are examined microscopically for size, shape, and other configurations.
Computer tomography (CT), magnetic resonance imaging (MRI), or both are used to scan the lung and perhaps other locations, such as the liver, upper abdomen, and brain, are used to determine the extent of the disease.

Physical Examination. A detailed physical examination of the whole body is very important to identify or rule out metastases to other areas and to determine the general condition of the patient. For example, questions about vertigo or headaches can help the doctor determine if the cancer has spread to the brain, while bone or joint pain might suggest the presence of bone metastases. The doctor will also look for head and neck symptoms that might reveal the presence of other tumors. Also, according to a 2000 review, the patient's weight loss and ability to function are two critical factors for predicting survival following treatment. Patients who are mobile and have lost less than 10% of their pre-treatment weight tend to have better survival rates.

Staging Systems

In lung cancer, disease stage at diagnosis is a major factor in determining how to treat the cancer and how long the patient can be expected to live. In general, survival is longest for patients with very early-stage disease and shortest for patients with very advanced disease that has spread to several regions of the body. Staging is based on the results of physical and surgical examinations, laboratory and imaging tests, and biopsies.

To determine the stage, medical professionals first categorize each tumor by size and by how far it has extended. This identification method is called the TNM system.
The TNM categories then determine the stage (numbered 0 to IV), which indicates how advanced the cancer is.

The TNM System

The TNM system is defined as T (for tumor), N (for regional lymph nodes), and M (for metastasis).

T refers to the size and extension of the tumor itself.

In TX and T0, the tumor is indicated by cancer cells in sputum or lung samples but cannot be visualized.

Tis: Carcinoma in situ. (The cells are cancerous, but the tumor does not show evidence of spreading.)

In T1, the tumor is 3 cm or less in dimension, is still contained in the lung or the membrane covering the lung (the visceral pleura), and has not reached the main airway (bronchus).

In T2, the tumor has one or more of the following features: greater than 3 cm; involves the main bronchus; 2 cm or more away from the ridge (the carina) at the lowest part of the windpipe (trachea); has invaded the visceral pleura; is associated with collapsed lung tissue (atelectasis) or obstructive inflammation of lung tissue but does not involve the entire lung.

In T3, a tumor of any size has directly invaded any of the following: chest wall, diaphragm, the membrane covering organs and structures in the chest, the outer wall of the membrane around the heart (pericardium); the tumor is in the main airway and less than 2 cm away from the carina but has not involved the trachea; the tumor is associated with atelectasis or obstructive inflammation of the entire lung.

In T4, the tumor has invaded any of the following: the area between the lungs (mediastinum), the heart, the great vessels, carina, trachea, esophagus, main portion of the spine; separate tumor nodules are present in the same lobe; the tumor is accompanied by a malignant pleural effusion (increased amount of fluid between the membrane and the lung).

N followed by 0 to 3 refers to whether the cancer has reached regional lymph nodes.

In stage N0, the regional lymph nodes are still cancer-free.

In N1, the cancer has spread to nearest lymph nodes around the airways, in the hilum (a depression in the lung where blood and lymph vessels enter), or in both. The tumor has extended directly into lymph nodes within the lung.

In N2, the cancer has spread to lymph nodes in areas in the middle of the chest that are still adjacent to the affected lung, to the nodes below the carina, or both regions.

In N3 the cancer has spread to lymph nodes in areas in the middle of the chest that are adjacent to the opposite lung, to the hilum in the opposite lung, to lymph nodes in nearby or opposite muscle tissue, or to lymph nodes above the clavicle (collar bone).

Stages M refer to metastasis.

In M0, metastasis has not occurred.

In M1 distant metastasis has occurred. This includes the presence of a separate tumor in a different lobe.