Lung cancer is when cells of the tissue of the lungs grow out of control.
This out of control growth causes problems such as the creation of a mass (tumor). Lung cancer can affect the tissue surrounding the mass and interfere with the organ function. It can also break away from the original mass and spread to other parts of the body (metastasis).
Non-Small Cell Lung Cancer (NSCLC)
Non-Small Cell Lung Cancer (NSCLC) is the most common type of lung cancer, making up 80-85% of all cases. It typically grows and spreads more slowly than small cell lung cancer (SCLC). NSCLC is staged based on the size of the primary tumor and if and where the cancer has spread (stages I, II, III, IV). See Stages of Lung Cancer for more information. Some lung cancer tumors are composed of cells from more than one type of NSCLC.
There are different kinds of NSCLC but the most commonly diagnosed are:
- Begins in the cells that form the lining of the lungs
- Has gland-like properties
- Makes up just over 30% of lung cancer diagnoses
Adenocarcinoma in situ (AIS) (formerly bronchioloalveolar carcinoma or BAC)
- Rare subset of adenocarcinoma that begins in the alveoli
- Can spread without destroying other tissues
- Makes up about 3% of lung cancer diagnoses
- Minimally invasive adenocarcinoma (MIA) is a classification added in 2011 to describe certain, smaller adenocarcinoma lung tumors.
Squamous cell carcinoma
- Begins in the thin, flat cells that line the passages of the respiratory tract
- Makes up just under 30% of lung cancer diagnoses
Large cell carcinoma
- Poorly differentiated (has none of the features that would allow it to be diagnosed as another type of NSCLC)
- Faster growing form of NSCLC
- Makes up about 9% of lung cancer diagnoses
Large cell neuroendocrine tumors
- Fastest growing type of NSCLC
- Makes up about 2% of lung cancer diagnoses
Small Cell Lung Cancer (SCLC)
Small Cell Lung Cancer (SCLC) makes up 15-20% of all lung cancer cases. It is a type of neuroendocrine tumor with cells that are smaller in size than most other cancer cells. It is a fast-growing cancer that spreads rapidly to other parts of the body. Some lung cancer tumors contain cells that are both SCLC and a form of NSCLC, often large cell. SCLC is usually staged as either limited or extensive, depending on if, and where, the cancer has spread. See Stages of Lung Cancer for more information.
Other types of tumors or cancers that can start in the lungs are:
A cancer of the lining of organs and not only can originate in the lungs but also the abdomen, heart, and chest. It is associated with exposure to asbestos. For more information on mesothelioma and its treatment, please visit the Mesothelioma Applied Research Foundation.
A type of neuroendocrine tumor. There are two types: typical and atypical. They usually start in the neuroendocrine (hormone producing) cells that line organs such as the small intestine but also the lungs. For more information on carcinoid tumors, please visit the Carcinoid Cancer Foundation.