Staging Systems:

Tests to Determine Cancer Stage. After diagnosing non-small cell lung cancer, the doctor 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 that may indicate whether the cancer is likely to spread, even if the tumor is small.
• Computer tomography (CT) and positron emission tomography (PET) are used to scan the lung and perhaps other locations, such as the liver, upper abdomen, and brain, to determine if and how far the disease has spread. Magnetic resonance imaging (MRI) is also sometimes used. Regardless of which imaging test is used, experts say the results should be confirmed with a biopsy.

Physical Examination. A detailed physical examination of the whole body is very important to identify or rule out the spread of cancer to other areas, and to determine the patient's general condition. For example, questions about dizziness or headaches can help the doctor determine if the cancer has spread to the brain. Bone or joint pain might suggest that the cancer has spread to the bone. The doctor will also look for head and neck symptoms that might indicate other tumors. Also, the patient's weight loss and ability to function are two very important 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, the stage of the disease at the time of diagnosis is a major factor in determining how to treat the cancer, and how long the patient can expect 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 areas of the body. Staging is based on the results of physical and surgical examinations, and laboratory and imaging tests, including 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) of the cancer.

The TNM System

TNM stands for Tumor, regional lymph Nodes, and Metastasis (cancer spread beyond the original tumor).

T refers to the size and spread of the tumor. In TX and T0, the tumor is indicated by cancer cells in sputum or lung samples but it cannot be seen.

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 size, is still contained in the lung or the membrane covering the lung, and has not reached the main airway.

In T2, the tumor has one or more of the following features:

• It is greater than 3 cm
• It involves the main airway
• It is 2 cm or more away from the ridge (the carina) at the lowest part of the windpipe
• It has invaded the pleura
• It is associated with collapsed lung tissue (atelectasis) or swelling that blocks part (but not all) of the lung

In T3, a tumor of any size has directly invaded any of the following:

• Chest wall
• Diaphragm
• Membrane covering organs and structures in the chest
• Outer wall of the membrane around the heart (pericardium)

In addition, one or more of the following conditions are present:

• The tumor is in the main airway, less than 2 cm away from the carina, but is not in the trachea (windpipe).
• The tumor is associated with a collapsed lung or swelling that blocks the entire lung.

In T4, the tumor has invaded any of the following:

• Area between the lungs (mediastinum)
• Heart
• Great vessels (the blood vessels that carry blood from the heart)
• Carina, trachea, or esophagus
• Main portion of the spine

In addition, one or both of the following occurs:

• Separate tumors are present in the same lobe
• The tumor is accompanied by an increased amount of fluid between the pleural membrane and the lung.

N followed by a number from 0 to 3 refers to whether the cancer has reached regional (in the area of tumor) lymph nodes.

• In stage N0, the regional lymph nodes are still cancer-free.
• In N1, the cancer has spread to the nearest lymph nodes around the airways, to the hilum (a central zone in the lung where blood and lymph vessels enter), or both. The tumor has extended directly into lymph nodes within the lung.
• In N2, the cancer has spread to lymph nodes in the middle of the chest next to the affected lung, to the nodes below the carina, or to both regions.
• In N3 the cancer has spread to lymph nodes in the middle of the chest that are next 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 collar bone.

M Stages refer to cancer spread (metastasis).

• In M0, spread has not occurred.
• In M1 distant spread has occurred. This includes the presence of a separate tumor in a different lobe of the lung.

Other Factors Determining Treatment Choices and Outcome

Staging factors are used to help determine treatment and outlook. The following suggest a more aggressive disease:

• The presence of respiratory symptoms
• A tumor larger than 3 cm
• High numbers of blood vessels in the tumor

Researchers are always looking for more accurate ways to determine lung cancer treatment and outlook. For example, some research involves specific biomarkers and related blood vessel development within tumors. These markers might eventually help predict the cancer's aggressiveness and determine the best treatment approach.