Lung cancer is cancer that starts in the lungs, and there are 2 major kinds. Small cell lung cancer (SCLC), which is named for the small cells that typically make up these cancers, account for 10-15% of all lung cancers. Non-small cell lung cancer (NSCLC) is the name used for all other types of lung cancer. NSCLC accounts for 85% to 90% of all lung cancer cases and can be divided into 3 main types.1

  • Adenocarcinoma
    Adenocarcinoma is the most common NSCLC. It primarily affects people who smoke, or used to smoke, but it is also the most common type of lung cancer seen in non-smokers. Adenocarcinoma comprises about 40% of all lung cancer cases, is more common in women, and it is more likely to affect younger people than other types of lung cancer. Adenocarcinoma is usually found in the outer region of the lung. It tends to grow slower.
  • Squamous cell carcinoma
    Squamous cell carcinoma occurs in the cells that line the airways inside your lungs. Squamous cell carcinoma accounts for approximately 25% to 30% of all lung cancer cases. It is often linked to a history of smoking and tends to be found in the middle of the lungs, near a large airway.
  • Large cell carcinoma
    Large cell carcinoma accounts for around 10% to 15% of lung cancers. It often grows and spreads fast, and may appear anywhere in the lung.

Causes of NSCLC

Traditionally, NSCLC has been linked with certain risk factors such as smoking. But lung cancer can strike anyone. Men and women of different ages and races, smokers, former smokers, and people who never smoked can get it.1

Doctors now believe that long-term exposure to cancer-causing substances can damage the cells in your lungs.2 Over time, this can cause gene mutations, or changes in the DNA sequence in a gene in these cells. However, changes can also happen when there is no clear cause. Some of these changes can cause the cells to grow and multiply abnormally, and this can lead to cancer.2,3

Non-small cell lung cancer (NSCLC):

A group of lung cancers that are named for the kinds of cells found in the cancer and how the cells look under a microscope. The 3 main types of non-small cell lung cancer are squamous cell carcinoma, large cell carcinoma, and adenocarcinoma. Non-small cell lung cancer is the most common kind of lung cancer.


A short piece of DNA, which tells the body how to build a specific protein.


The molecules inside cells that carry genetic information and pass it from one generation to the next. Also called deoxyribonucleic acid.