What is Non-Small Cell Lung Cancer?

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When your lung cells grow abnormally and out of control, lung cancer begins. As these cancerous cells increase in number, they form a tumor and can spread to other body regions.

About Non-Small Cell Lung Cancer

About 80 to 85 percent of lung cancers in America are non-small cell lung cancer. About ten to 15 percent of lung cancers are small cell lung cancer.

Non-small cell lung cancer includes multiple subtypes. These subtypes start in different lung cells but are still classified as non-small cell lung cancer because their treatment approaches and prognosis have much in common.

The three primary subtypes of non-small cell lung cancer include adenocarcinoma, squamous cell carcinoma and large cell carcinoma. There are also other subtypes that are less common.


Forty percent of lung cancers in the U.S. gain a diagnosis of adenocarcinomas. Lung cells normally responsible for secretion of mucus or other substances develop these cancers when the cells are young.

Although mostly smokers and former smokers receive this diagnosis, it also affects more non-smokers than other types of lung cancers. More women suffer adenocarcinoma than men. The disease also occurs in younger people more than other lung cancers.

Adenocarcinoma typically occurs in your lung’s outer parts, where it grows more slowly than other types of lung cancer. More people find this lung cancer through early diagnosis and before it spreads, versus other lung cancers. But when the cancer is found depends on individual patients and their healthcare.

One of the most treatable lung cancers is adenocarcinoma in situ, once called bronchioloalveolar carcinoma.

Squamous Cell Carcinoma

About one quarter to one third of lung cancers are the subtype squamous cell carcinoma. Flat cells lining the inside of your lungs’ airways are squamous cells. This is where this sub-type of non-small cell lung cancer begins. A history of smoking is the biggest risk factor for this lung cancer, where the disease is usually discovered in the lungs’ central part near the primary airway.

Large Cell Carcinoma

Sometimes called undifferentiated carcinoma, this lung cancer occurs in ten to 15 percent of non-small cell lung cancer cases. It appears anywhere in the lungs, growing and spreading very quickly. Its rapid growth and spread make it aggressive and harder to treat.

Other subtypes of lung cancer less common in the United States include adenosquamous carcinoma and sarcomatoid carcinoma.