Non-small cell lung cancer (NSCLC) is the most common type of malignancy (cancer) that affects the lungs, accounting for nearly 85% of lung cancers. While there are several types of non-small cell lung cancer, the three most common types are 1) adenocarcinoma, 2) squamous cell carcinoma, and 3) large cell carcinoma.
Adenocarcinoma occurs in the outer region of the lung and is the most common form of non-small cell lung cancer in the United States.
Squamous cell carcinoma occurs in the center of the lung next to the bronchus (airway) and accounts for 25% of non-small cell cancers.
Large cell carcinoma occurs in any part of the lung and accounts for 10% of non-small cell lung cancers.
In addition to these three common types of non-small cell lung cancer, there are some less common types: pleomorphic (variable in size and shape), carcinoid tumor, salivary gland carcinoma, and unclassified carcinoma.
Non-small lung cancer is classified in the following stages:
Occult stage – Cancer is undetectable (hidden).
Stage 0 – Carcinoma in situ, or the earliest stage at which non-small lung cancer can be detected.
Stage I – Cancer is only in the lung with no spread.
Stage II – Cancer is in the lung and close lymph nodes.
Stage III – Cancer is in the lung and median (middle) chest lymph nodes, which is known as locally advanced lung cancer. This stage has two subtypes: 1) Stage IIIA – Cancer has only spread to same side chest lymph nodes; and 2) Stage IIIB – Cancer has spread to opposite side chest lymph nodes, or above the collarbone.
Stage IV – Advanced lung cancer that has spread to both lungs, the fluid surrounding the lungs, or other organs or parts of the body.