Lung Cancer Types
What You Need to Know
- The most common types of lung cancer include lung nodules, non-small cell lung cancer, small cell lung cancer and mesothelioma.
- Rare lung cancers often don't originate in the lung.
- Rare lung cancers vary according to size, recommended treatment options and rate of metastasis.
The most common types of lung cancer are those found right in the lungs. Other rarer types of cancer may also occur in the lungs and chest wall.
Lung nodules are small masses of tissue. They may be benign, precancerous or metastatic tumors that have spread from other parts of the body. Generally, a larger nodule is more likely to be cancerous than a smaller one.
Lung nodules are often found when a patient is being tested for unrelated symptoms, such as abdominal pain or an injury.
Non-Small Cell Lung Cancer
Non-small cell lung cancer is the most common type of lung cancer. It grows and spreads more slowly than small cell lung cancer. The three main kinds of non-small cell lung cancer are named for the type of cells in the tumor:
Adenocarcinoma is the most common type of lung cancer in the United States and usually begins along the outer sections of the lungs. It is also the most common type of lung cancer in people who have never smoked.
Large cell carcinomas are a group of cancers with large, abnormal-looking cells. These tumors may begin anywhere in the lungs and tend to grow quickly.
Squamous cell carcinoma is also called epidermoid carcinoma. It often begins in the bronchi near the middle of the lungs.
For non-small cell lung cancers that have not spread beyond the lung, surgery is used to remove the cancer. Surgery may also be used in combination with radiation therapy and chemotherapy in cancers that are more advanced. These treatments can also be given prior to surgery to shrink tumors and prevent the spread of cancer cells through the blood stream. This is called neoadjuvant therapy.
Small Cell Lung Cancer
Almost all cases of small cell lung cancer are due to cigarette smoking. It is a fast-growing cancer that spreads much more quickly than other types of lung cancer. There are two different types of small cell lung cancer:
Small cell carcinoma (oat cell cancer; most small cell lung cancers are of the oat cell type)
Combined small cell carcinoma
Surgery is most commonly used in non-small cell lung cancers and less frequently in small cell lung cancer, which tends to spread more quickly to other parts of the body. Chemotherapy is the most common treatment for small cell lung cancer, as these medicines circulate throughout the body killing lung cancer cells that may have spread outside of the lung. Radiation therapy is frequently used in combination with chemotherapy when the tumor is confined to the lung and other areas inside of the chest. Radiation therapy may also be used to prevent or treat the development of small cell lung cancer that has spread to the brain (metastasis). In radiation therapy, precisely targeted X-rays are used to destroy localized cancer cells. Radiation therapy can be used to prevent tumor recurrence after surgery, to treat tumors in patients who are not candidates for surgery or to treat tumors causing symptoms in other parts of the body.
Mesothelioma is a rare cancer of the chest lining, most often caused by asbestos exposure. It accounts for about 5 percent of all lung cancer cases. Mesothelioma develops over a long period time, from 30 to 50 years between exposure to asbestos and getting the cancer.
Most people who develop mesothelioma worked in places where they inhaled asbestos particles.
Once mesothelioma has been diagnosed, it is staged, which tells the patient and doctors how large the tumor is and where is has progressed beyond the initial site.
Chemotherapy, radiation and surgery can all be part of the treatment for mesothelioma. Combined approaches that utilize these therapies together — particularly using chemotherapy prior to surgery, as well as new drugs that specifically target mesothelioma cells — are currently being tested.
Lung cancer specialists at Johns Hopkins use surgery, radiation, chemotherapy or all three to treat mesothelioma.
Chest Wall Tumors
Chest wall tumors are rare. Like other cancers, tumors found in the chest wall may be malignant or benign. Malignant tumors must be treated. Benign tumors will be treated depending on where they are located and the symptoms they cause. If a tumor presses against a lung so that a patient can't breathe, for example, then it must be treated.
Types of Chest Wall Tumors
Tumors found in the chest wall are also categorized by whether they are primary tumors (starting in the chest wall) or metastatic tumors (spread to the chest wall from cancer that started elsewhere, such as in the breast). All metastatic tumors are malignant. In children, most chest wall tumors are primary, while they are more often metastatic in adults. Primary tumors start in the bones or muscles located in the chest wall.
Sarcomas — tumors that start in bone or muscle tissue, or more rarely in other types of tissue — are the most common type of primary tumor found in the chest wall.
Some cancers in the lung are the result of pulmonary metastasis — cancer that began in another part of the body and spread to the lung through the lymphatic system or bloodstream. Almost any cancer can metastasize to the lung. Some cancers that often spread to the lung are:
Rare Cancer Types
Carcinoid tumors are rare cancers that most often appear in the stomach or intestines. However, they sometimes start in the lung. Carcinoid tumors can be classified as either typical or atypical.
Typical carcinoids grow slowly and don't often spread beyond the lungs. Nine out of 10 lung carcinoids are typical carcinoids.
Atypical carcinoids grow faster and are slightly more likely to spread outside the lungs.
Carcinoid tumors are also sometimes categorized by where they start in the lung:
Central carcinoids form in the bronchi, which are the large airways located near the center of the lungs. Most lung carcinoid tumors start there. These carcinoids are almost always typical carcinoids.
Peripheral carcinoids develop in the smaller airways on the edges of the lungs and they too are almost always typical carcinoids.
Lung carcinoid tumors are most often treated by surgery. Chemotherapy and radiation therapy may be used as adjunct therapies or if surgery is not possible.
Mediastinal tumors are rare tumors that develop in the mediastinum, the area of the chest that separates the lungs. It is surrounded by the breastbone in front and spine in the back.
They can be benign or cancerous, forming from any tissue that exists or passes through the chest cavity. Most mediastinal tumors in children are benign while many mediastinal tumors in adults are cancerous. Because they are located in the chest cavity where the heart and major arteries are or near the spinal cord in back, both benign and malignant tumors must be treated.
There are several types of mediastinal tumors:
Germ cell tumors: These cancers are very treatable and often curable. They develop from reproductive cells and are more often found in the reproductive systems of both men and women. When found outside the reproductive system, they may also be called extragonadal germ cell tumors. How these cells move from the reproductive system to the mediastinum is not currently known.
Lymphomas: These malignant tumors start in the lymphatic system and include Hodgkin's lymphoma and non-Hodgkin's lymphoma. The lymphatic system is a complex network of capillaries, thin vessels, valves, ducts, nodes and organs that helps to protect and maintain the fluid environment of the body by filtering and draining lymph. In rare case, lymphoma can originate in the lungs.
Teratomas: These malignant tumors are made of cysts that contain one or more layers of embryonic cells. The layers are called ectoderms, mesoderms and endoderms. A rare cancer, teratomas occur most often in young men in their twenties and thirties. The tumors are most often located in the chest area. By the time the cancer is diagnosed, they have often spread. A number of other cancers are often associated with these tumors, including:
Acute myelogenous leukemia (AML)
Embryonal rhabdomyosarcoma (ERMS)
Small cell undifferentiated carcinoma
Thymomas: Thymomas and thymic carcinoma are rare cancers in which cancerous cells form on the outside of the thymus, a small organ in the upper chest that makes white blood cells. Thymomas are rarely malignant, grow slowly and don't often spread beyond the thymus. Thymoma is linked with myasthenia gravis and other autoimmune diseases (diseases that cause the immune system to attack healthy cells and tissue).
Thymic carcinomas grow more quickly and have usually spread by the time the cancer is diagnosed. People with thymoma often have autoimmune diseases as well.