There are two types of lung cancer: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). They have different cells, spread in different ways and are treated differently.

Non-small cell lung cancer generally grows and spreads less quickly than small cell lung cancer. It accounts for 87 percent of lung cancers, according to the American Cancer Society (ACS). There are several subtypes of NSCLC:

• Adenocarcinoma. Cancer in the mucus-producing glandular cells in the outer part of the lungs in the bronchi and bronchioles. This is the most common type of lung cancer and is most common in women and non-smokers. This cancer rarely shows symptoms in the early stages and therefore may be metastasized by the time of diagnosis. However, it is also most responsive to treatment. About 40 percent of lung cancers are this type.
  
  
• Squamous (epidermoid) cell carcinoma. Cancer of the cells lining the bronchi or airways in the central part of the lungs. These cells are thin and flat and look like fish scales. They can be easily found in sputum, which assists in early detection and cure. This form of lung cancer is most common in men. This is the slowest growing of the three non-small cell types and 25 to 30 percent of lung cancers are this type.
  
  
• Large cell carcinoma. Cells originating in the peripheral parts or edges of the lungs. These cells are large, grow and spread aggressively to distant organs. This lung cancer is strongly associated with smoking with 10 to 15 percent of lung cancers being large cell carcinoma.

About 20 percent of lung cancers are small cell lung cancers, also called oat cell cancer because of a resemblance to oat grains. This type of cancer generally is more aggressive than the non-small cell cancers. It begins in the cells of the bronchi and can quickly spread before any symptoms appear. This cancer metastasizes early to distant organs and tissues such as the brain, bone and liver and is particularly life-threatening. The cell type does respond to chemotherapy but is often widely metastasized at the time of diagnosis. Approximately 90 percent of people with small cell lung cancer are current or past smokers.

There are more rare forms of lung cancer, which include:

• Carcinoid tumors. They are slow growing, often benign and usually cured by surgery. Fewer than 5 percent of lung tumors are of this type, according to the ACS.
  
  
• Adenosquamous carcinoma. Cancer with features that are a mix of adenocarcinoma and squamous cell.
  
  
• Bronchioalveolar carcinoma. A subtype of adenocarcinoma that often does not involve bleeding and death of tissue.
  
  

  

  
  
• Sarcoma. Cancer of soft connective tissue, including muscle, nerves and fat. Risk factors include certain hereditary syndromes, damage to the lymphatic system and exposure to toxic chemicals.
  
  
• Lymphoma. Cancer of the lymphatic system. Risk factors include immune disorders, aging and genetic mutations caused by exposure to chemicals, radiation or other sources.

In addition, benign (noncancerous) growths called carcinoid tumors sometimes develop in the lungs. Surgery is usually successful in removing these growths.