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Article written by Emily Wagner, M.S.
Different types of lung cancer are defined by the location of the cancer and the type of cell it originates from. The type of lung cancer will dictate treatment plans and the overall outlook of the disease.
There are two main types of lung cancer: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Overall, NSCLC accounts for 84 percent of cases and SCLC for 13 percent. Rare subtypes of lung cancer can also be found in less than 5 percent of all cases.
There are several subtypes of NSCLC, which are often grouped together because they have similar treatments and outlooks. About 90 percent of NSCLC cases are caused by smoking. These cancers are often treated through surgery, chemotherapy, targeted therapy (medication that specifically recognizes and attacks cancer cells), and radiation. A person’s disease outlook is generally based on how early the cancer was diagnosed and whether cancer cells have spread to other parts of the body.
Lung adenocarcinoma is cancer of the cells that secrete mucus, known as glandular cells. These cells are found in the alveoli, or smaller airways, of the lung. Adenocarcinomas tend to develop more along the outer edges of the lungs, and grow at a slower rate than other lung cancers.
Adenocarcinomas are the most common type of lung cancer, accounting for 40 percent of all cases. Adenocarcinomas are more likely to develop in women and in younger people between the ages of 20 and 46.
Adenocarcinoma in situ is a type of adenocarcinoma that tends to have a better outlook compared to other types of lung cancer.
Squamous cell carcinoma (also known as epidermoid carcinoma) is cancer of the cells that line the inside of the airways in the lungs. These cells look similar to fish scales under a microscope. Squamous cell carcinomas tend to develop in the central part of the lung or in one of the main airways (bronchi).
Squamous cell carcinomas account for 30 percent of all lung cancers. They are more strongly associated with cigarette smoking than any other type of NSCLC. Other risk factors for developing squamous cell carcinoma include a family history of lung cancer, older age, and exposure to secondhand smoke or carcinogens like metal and mineral dust, radon, or asbestos.
Large cell carcinoma is a general diagnosis for when cancer cells, examined under a microscope, appear too large to be small cell lung cancer and also do not look like adenocarcinoma or squamous cell carcinoma. Large cell carcinomas can be found anywhere in the lung, but are usually closer to the outer surface.
As more accurate methods for diagnosis are discovered, large cell carcinomas now account for only 2 percent of lung cancer cases. Most cases of large cell carcinoma are diagnosed in men.
Large cell neuroendocrine carcinoma is a subtype of large cell carcinoma that grows rapidly and is very similar to SCLC.
Pulmonary sarcomatoid carcinoma is a rare subtype of NSCLC that accounts for 0.1 percent to 0.4 percent of all lung cancers. Even in the early stages of disease, it can be more aggressive than other types of NSCLC. Most cases of sarcomatoid carcinoma are diagnosed in older men who smoke heavily.
Adenosquamous carcinoma is another rare subtype that accounts for 0.4 percent to 4 percent of NSCLC cases. As the name suggests, the tumors in this subtype show components of both adenocarcinomas and squamous cell carcinomas, with each element making up more than 10 percent of the tumor. The prognosis for adenosquamous carcinoma is generally worse than for adenocarcinoma or squamous cell carcinoma alone.
SCLC is almost always caused by smoking. These tumors grow more quickly and aggressively than NSCLC, making them harder to treat. People with SCLC often do not have a very good disease outlook, although how well treatment works depends on how early the cancer was diagnosed. There are two main subtypes of SCLC — small cell carcinoma and combined small cell carcinoma.
Small cell carcinoma is cancer of the epithelial cells that line the bronchi in the lungs. It is also known as oat cell cancer because, under a microscope, the oval-shaped cells look like oat grains. Almost all cases of small cell carcinoma are due to smoking, and it rarely develops in people who have never smoked.
Roughly 70 percent of small cell carcinoma cases will have spread by the time they are diagnosed. Since it is a quick-growing cancer, it tends to respond well to chemotherapy and radiation.
Combined small cell carcinoma occurs when a small cell carcinoma tumor has additional components of NSCLC subtypes (adenocarcinoma, squamous cell carcinoma, or large cell carcinoma). This is a rare subtype of SCLC, accounting for only 2 percent to 5 percent of all lung cancers.
Although most lung tumors are classified as NSCLC or SCLC, a small percentage of lung cancer cases don’t fall into either type. These tumors often have different causes, treatments, and outlooks than NSCLC and SCLC.
Lung carcinoid tumors, or simply lung carcinoids, are a type of lung cancer that develops in specialized lung cells known as neuroendocrine cells. These cells function like both nerve cells and hormone-producing endocrine cells. In addition to the lungs, neuroendocrine cells can also be found in the stomach and intestines.
There are two types of lung carcinoid tumors — typical and atypical carcinoids. Typical carcinoids grow more slowly and rarely outside of the lungs. They account for nearly 90 percent of lung carcinoids. Cigarette smoking does not appear to be linked with cases of typical carcinoids.
Atypical carcinoids grow faster, with cells that divide quickly. They are more likely to spread outside the lungs. Atypical carcinoids are much more rare than typical carcinoids, and may be linked to cigarette smoking.
A lung nodule is a mass or abnormal area usually found through a CT scan. Most lung nodules are benign (noncancerous), and are usually the result of scar tissue or a previous infection. Still, other tests will need to be run to make sure the nodule is not cancer.
If a nodule is found, repeat CT scans will be performed to see if the nodule changes in size or shape over time. If the nodule has grown, the doctor will perform a positron emission tomography (PET) scan to see if it is cancerous. A biopsy of the nodule may be sent to a pathologist who will look at the cells under a microscope. If cancer is found, the pathologist will identify the type, and your doctor will discuss the next steps with you.
Mesothelioma is cancer of the mesothelium, which lines the inside of the chest, abdomen, and heart and produces a lubricant that allows the organs to move against one another. Mesothelium also covers the outer surface of most internal organs.
Pleural mesothelioma is the most common type of mesothelioma, accounting for 80 percent to 90 percent of cases. This cancer starts in the pleura, which is the tissue lining the lungs and chest wall. The most common cause of pleural mesothelioma is inhaling asbestos fibers.
Malignant granular cell tumors are extremely rare, mostly benign growths that begin in the skin, tongue, breast, and lungs. There are very few reported cases in scientific literature. Of cases reported in the lungs, all have been benign.
Mediastinal tumors grow in the area of the chest that separates the lungs, known as the mediastinum. These rare tumors are typically diagnosed in people between the ages of 30 and 50. Mediastinal tumors can be benign or cancerous and occur in different areas of the mediastinum.
The chest wall is a broad set of structures that surround and protect the lungs. It includes cartilage, bone, muscle, lymph nodes, blood vessels, fat, and skin. Primary chest wall tumors originate in the chest wall, while secondary chest wall tumors can occur when cancer has spread from the nearby lungs or breasts or metastasized from another cancer in the body.
NUT carcinoma, or NUT midline carcinoma, is so rare that there is no reliable data on how many people have had it. It is usually found in the head, neck, and lungs. The cancer develops from squamous cells and is caused by a chromosomal change involving the NUT gene.
Pancoast’s tumors, also known as superior sulcus tumors, are a type of NSCLC that develops in the upper portion of either the left or right lung. It is a rare subtype, accounting for only 3 percent to 5 percent of all lung cancers. While the majority of Pancoast’s tumors are NSCLC, they can also be caused by tuberculosis, lymphoma, or other chest wall tumors.
Salivary gland-type carcinomas are a rare type of lung cancer, occurring in less than 1 percent of lung cancer cases. The two most common subtypes are mucoepidermoid carcinoma and adenoid cystic carcinoma. Mucoepidermoid carcinomas are generally localized (have not spread) and have a good prognosis, while adenoid cystic carcinomas tend to be discovered at a more advanced stage and often cannot be surgically removed.
Certain types of cancer tend to metastasize to other parts of the body more frequently than others. When cancer spreads into the lungs, it is usually from:
While these cancers more commonly spread to the lungs, almost any cancer is able to spread there.
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