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Dictionary of Cancer Terms
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stage I non-small cell lung cancer (... KAN-ser)

 Stage I is divided into stages IA and IB. In stage IA, the tumor is in the lung only and is 3 centimeters or smaller. In stage IB, one or more of the following is true: (1) the tumor is larger than 3 centimeters; (2) cancer has spread to the main bronchus of the lung, and is at least 2 centimeters from the carina (where the trachea joins the bronchi); (3) cancer has spread to the innermost layer of the membrane that covers the lungs; and/or (4) the tumor partly blocks the bronchus or bronchioles and part of the lung has collapsed or developed pneumonitis (inflammation of the lung).

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Two-panel drawing of stage I non-small cell lung cancer; first panel shows stage IA with cancer in one lung; the trachea, lungs, lymph nodes, right main bronchus, bronchioles, and diaphragm are also shown; second panel shows stage IB with cancer in the left lung and near the left main bronchus. The inset shows a close-up of the lung, chest wall, and pleura with cancer spreading from the lung into the innermost layer of the pleura.

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