There are two main types of lung cancer: non-small cell lung cancer and small cell lung cancer. Each looks different under a microscope and grows and spreads differently. But both types of lung cancer share the same staging system. Your doctor will consider the type and the stage of lung cancer in determining the possible options for treatment.

Non-small cell lung cancer

Non-small cell lung cancer is more common than small cell lung cancer. About 85% of all lung cancers are non-small cell cancer. It typically grows and spreads more slowly than small cell lung cancer.

These include:

• Adenocarcinoma. This type often begins near the outside surface of the lung and may vary both in size and how fast it grows. Adenocarcinoma is likely to spread to lymph nodes and other organs. This type is more common than other types of lung cancer in women, nonsmokers, and former smokers.
• Squamous cell carcinoma, also called epidermoid carcinoma. This type usually begins in one of the larger airway tubes (bronchi), typically grows more slowly than the other types of non-small cell cancer, and may vary in size from very small to very large. Squamous cell carcinoma may spread to nearby lymph nodes or to other organs.
• Large cell carcinoma. This type often begins near the surface of the lung and usually is large when diagnosed. Large cell carcinoma is likely to spread to lymph nodes and other organs.

Small cell lung cancer

Small cell lung cancer is less common than non-small cell lung cancer. About 15% of lung cancers are small cell. This type of cancer grows very rapidly and in most people has already spread to other organs in the body by the time it is diagnosed.

Small cell lung cancer is divided into two categories:

• Limited disease, where the tumor is only in one lung, in the tissues between the lungs, and in nearby lymph nodes.
• Extensive disease, which means the tumor has spread beyond the lung and nearby lymph nodes, or pleural effusion is present.