There are three ways that cancer spreads in the body.
The three ways that cancer spreads in the body are:
- Through tissue. Cancer invades the surrounding normal tissue.
- Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
- Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.
When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.
The following stages are used for non-small cell lung cancer:
Occult (hidden) stage
In the occult (hidden) stage, cancer cannot be seen by imaging or bronchoscopy. Cancer cells are found in sputum (mucus coughed up from the lungs) or bronchial washing (a sample of cells taken from inside the airways that lead to the lung). Cancer may have spread to other parts of the body.
Stage 0 (carcinoma in situ)
In stage 0, abnormal cells are found in the lining of the airways. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.
Stage I non-small cell lung cancer. In stage IA, cancer is in the lung only and is 3 cm or smaller. In stage IB, the cancer is (a) larger than 3 cm but not larger than 5 cm, (b) has spread to the main bronchus, and/or (c) has spread to the innermost layer of the lung lining. Part of the lung may have collapsed or become inflamed (not shown).
In stage I, cancer has formed. Stage I is divided into stages IA and IB:
- Stage IA: The tumor is in the lung only and is 3 centimeters or smaller.
- Stage IB: Cancer has not spread to the lymph nodes and one or more of the following is true:
- The tumor is larger than 3 centimeters but not larger than 5 centimeters.
- Cancer has spread to the main bronchus and is at least 2 centimeters below where the trachea joins the bronchus.
- Cancer has spread to the innermost layer of the membrane that covers the lung.
- Part of the lung has collapsed or developed pneumonitis (inflammation of the lung) in the area where the trachea joins the bronchus.