There are two main types of lung cancer: non-small-cell lung cancer (NSCLC) and small-cell lung cancer (SCLC). Several subtypes exist within these categories, and there are a few other, relatively rare types as well.

Some tumors contain cells that are both SCLC and a form of NSCLC (often large cell), according to the GO₂ for Lung Cancer foundation. (1)

Doctors must know the type of cancer you have to determine the best lung cancer treatment, because each kind requires a different approach.

Non-Small-Cell Lung Cancer

Non-small-cell lung cancer (NSCLC) is the most common type of lung cancer, accounting for 80 to 85 percent of all cases, according to the American Cancer Society (ACS). (2)

There are different kinds of NSCLC, arising from different kinds of lung cells, but the ones most commonly diagnosed are:

Adenocarcinoma
Squamous cell carcinoma
Large-cell carcinoma

Adenocarcinoma

Adenocarcinoma represents about 30 percent of all lung cancers. (1)

The American Cancer Society offers the following facts about adenocarcinoma (2):

It typically develops in cells in the outer part of the lung that would normally secrete substances such as mucus.
It occurs mostly in smokers, but it is also the most common lung cancer to affect nonsmokers.
It is more prevalent in women than men.
If you’re young and diagnosed with lung cancer, the type is most likely to be adenocarcinoma.
It tends to be diagnosed earlier than other kinds of lung cancers.

There’s a rare subset of adenocarcinoma that begins in the alveoli (the tiny air sacs in the lungs), called adenocarcinoma in situ (AIS), previously known as bronchioloalveolar carcinoma.

AIS tumors account for about 3 percent of lung cancer diagnoses. (1)

People with AIS tend to have a better prognosis (outlook) than those with other types of lung cancer. (2)

Squamous-Cell Carcinoma

About 30 percent of all lung cancers are squamous-cell carcinomas. (1)

This type of lung cancer starts in the thin, flat cells that line the passages of the respiratory tract, most commonly in the central part of the lung, near a main airway.

Squamous-cell carcinomas are linked to smoking. (2)

Large-Cell Carcinoma

Large-cell carcinoma makes up about 9 percent of all lung cancers. (1)

This cancer can show up in any part of the lung. It usually grows and spreads rapidly, which makes treatment a challenge.

A type of large-cell carcinoma, called large-cell neuroendocrine carcinoma, is the fastest-growing NSCLC and resembles a small-cell carcinoma. (2)

Other Subtypes of NSCLC

Other subtypes of NSCLC include adenosquamous carcinoma and sarcomatoid carcinoma. These are much less common forms of lung cancer. (2)

Small-Cell Lung Cancer

Small-cell lung cancer (SCLC), sometimes called oat-cell carcinoma, accounts for about 10 to 15 percent of lung cancers. (2)

This cancer is a type of neuroendocrine tumor containing cells that are smaller than most other cancer cells.

SCLC is fast-growing, with most people who have it receiving a diagnosis only after the cancer has spread. (2)

Almost all cases of SCLC are related to smoking; it is extremely uncommon in someone who has never smoked. (3)

What Is the Most Aggressive Type of Lung Cancer?

Small-cell lung cancer is the most aggressive kind of lung cancer.

Although the cancer cells are small, they grow and spread quickly to other parts of the body, such as the brain, liver, and bone. (3)

Because SCLC is fast-growing, it tends to respond well to chemotherapy and radiation treatment, though for most people it will recur. (2)

Other Types of Lung Cancer

Other types of tumors can occur in the lungs, including:

Lung Carcinoid Tumors These tumors typically grow slowly. They account for fewer than 5 percent of lung tumors. (2)

Mesothelioma This type of cancer is most commonly found in the lining of the lung, though it can also start in the lining of the abdomen, heart, or chest. It is linked to exposure to the mineral asbestos. (1)

Rare Tumors Other types of cancer that can occur in the lungs include adenoid cystic carcinoma, sarcoma, lymphoma, thymoma, and hamartoma (benign lung tumors). (2)

Cancer That Spreads to the Lungs Cancer that starts in another organ can metastasize to the lungs, although this isn’t considered lung cancer. For instance, a tumor that starts in the liver but spreads to the lungs is still considered a liver tumor, and should be treated accordingly. (2)

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