Lung cancer types

Non-small cell lung cancer

Non-small cell lung cancer is the most common type of lung cancer. It accounts for nearly nine out of every 10 cases, and usually grows at a slower rate than SCLC. Most often, it develops slowly and causes few or no symptoms until it has advanced.

Types of non-small cell lung cancer

There are three main types of non-small cell lung cancer:

Adenocarcinoma of the lung: Lung adenocarcinoma is the most common form of lung cancer, accounting for 30 percent of all cases overall and about 40 percent of all non-small cell lung cancer occurrences. Adenocarcinomas are found in several common cancers, including breast cancer, prostate cancer and colorectal cancer. Adenocarcinomas of the lung are found in the outer region of the lung, in glands that secrete mucus and help us breathe. Symptoms include coughing, hoarseness, weight loss and weakness.

Adenocarcinomas form in cells that typically produce mucus and are diagnosed mainly in current and former smokers.

Other key facts about adenocarcinoma include:

• It’s the most common cancer among people who never smoked.
• It’s the more common form of lung cancer among young people.
• Women are more prone than men to develop this cancer.
• Doctors often detect adenocarcinoma before it spreads.
• For adenocarcinoma in situ (when doctors find abnormal cells in glandular tissue that lines the lungs), the outlook is often much better compared with other types of lung cancer.

Learn more about adenocarcinoma of the lung

Squamous cell: This type of lung cancer is found centrally in the lung, where the larger bronchi join the trachea to the lung, or in one of the main airway branches. Squamous cell lung cancer is responsible for about 30 percent of all non-small cell lung cancers, and is generally linked to smoking.

Large-cell undifferentiated carcinoma: Large-cell undifferentiated carcinoma lung cancer grows and spreads quickly and can be found anywhere in the lung. This type of lung cancer usually accounts for 10 to 15 percent of all cases of NSCLC. Large-cell undifferentiated carcinoma tends to grow and spread quickly.

Other key facts about large-cell undifferentiated carcinoma include:

• This type of lung cancer may grow and spread quickly, making it difficult to treat.
• Another fast-growing subtype, called large cell neuroendocrine carcinoma, shares similarities with small cell lung cancer.

Other less common subtypes of NSCLC include sarcomatoid carcinoma and adenosquamous carcinoma.

Doctors determine the severity of NSCLC through the staging process, which reveals whether the cancer has spread throughout the lungs or to other parts of the body.

NSCLC is classified by the following stages:

• Occult, or hidden, stage
• Stage 0
• Stage 1
• Stage 2
• Stage 3
• Stage 4

To diagnose and stage NSCLC, doctors use a number of tests, including:

• Bone marrow aspiration and biopsy
• Bone scan
• Computed tomography (CT) scan
• Magnetic resonance imaging (MRI)
• Positron emission tomography (PET) scan
• Pulmonary function test

Treatments for non-small cell lung cancer include:

• Chemotherapy
• Cryotherapy
• Immunotherapy
• Laser therapy
• Photodynamic therapy
• Radiation therapy
• Surgery
• Targeted therapy

Small cell lung cancer

Small cell lung cancer is also known as “oat-cell” cancer because the cells look like oats under the microscope. It often starts in the bronchi, then quickly grows and spread to other parts of the body, including the lymph nodes. This type of lung cancer represents fewer than 20 percent of lung cancers and is typically caused by tobacco smoking. It is also the most aggressive form of lung cancer.

SCLC often grows and spreads more quickly than NSCLC, but usually responds well to chemotherapy and radiation treatment. SCLC often recurs in many people who develop it.

Types of small cell lung cancer

Small cell lung cancer is divided into two types, named for the kinds of cells found in the cancer and how the cells look when viewed under a microscope:

• Small cell carcinoma (oat-cell cancer)
• Combined small cell carcinoma

Doctors may use these tests to diagnose and stage SCLC:

• Bone scan
• CT scan
• MRI)
• PET scan

Small cell lung cancer may be very aggressive and requires immediate treatment. Treatments for small cell lung cancer include:

• Chemotherapy
• Immunotherapy
• Laser therapy
• Radiation therapy
• Surgery

Lung carcinoid tumors

Lung carcinoid tumors, or lung carcinoids, are an uncommon type of lung cancer that typically grows at a slower rate and accounts for about 1 to 2 percent of all lung cancer cases, according to the ACS. 

They typically form in cells in the lungs called neuroendocrine cells. 

The two main subtypes of lung carcinoid tumors are typical carcinoids and atypical carcinoids: 

• Typical carcinoids, which usually grow at a slow pace, comprise 90 percent of lung carcinoid cases. They don’t often spread past the lungs nor appear to be related to smoking. The average age for this diagnosis is 45. 
• Atypical carcinoids grow faster, may have greater chances of spreading to other organs, and may be related to smoking. They occur less frequently than typical carcinoids and have cells that resemble those of a fast-growing lung tumor. The average age for this diagnosis is 55.

Doctors sometimes classify lung carcinoid tumors based on where they first developed in the lungs: 

• Central carcinoids comprise the majority of lung carcinoid cases. These tumors develop in the bronchi, which are large airways near the middle of the lungs. Most central carcinoids are typical carcinoids.
• Peripheral carcinoids develop in the bronchioles, which are smaller airways near the outer regions of the lungs. The majority of peripheral carcinoids are also typical carcinoids.

Metastatic lung cancer

Because symptoms do not always develop when lung cancer is present, it is common for the cancer to metastasize before it is diagnosed. Even though the cancer may have formed a tumor in a new location in the body,

Learn more about metastatic lung cancer

Rare forms of lung cancer

Several types and subtypes of lung cancer are very rare. They include:

• Adenosquamous carcinoma of the lung, a hybrid of adenocarcinoma and squamous cell lung cancer
• Large cell neuroendocrine carcinoma, an aggressive subtype of non-small cell lung cancer
• Salivary gland-type lung carcinoma, which is most often found in the central airways of the lungs
• Lung carcinoids, a rare type of cancer often found in younger than average lung cancer patients
• Mesothelioma, a rare type of cancer that develops in thin tissue called mesothelium, which lines the lungs and abdomen

Mediastinal tumors are also rare and develop in the mediastinum, which separates the lungs in the center of the chest.

The trachea (or windpipe), esophagus, heart, connective tissues and other organs are part of the mediastinum. In adults, most mediastinal tumors form in the front of the mediastinum and typically fall into one of the following categories:

• Germ cell tumors
• Malignant, or cancerous, lymphomas
• Thymomas

Other extremely rare forms of lung cancer include sarcomatoid carcinoma of the lung and malignant granular cell lung tumors.

Next topic: What is adenocarcinoma of the lung cancer?