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Lung Cancer
 Lung cancers are tumors that form in tissues of the lung, usually in the cells lining air passages. Lung cancer is one of the most common cancers: about 12 million people are diagnosed with lung cancers annually worldwide. In the United States, there are more deaths from lung cancer than colorectal cancer, breast cancer and prostate cancer combined.
The lungs are two sponge-like organs found in the chest cavity that form part of the respiratory system. Each of our two lungs is slightly different. The right lung is slightly larger and has three sections, called lobes. The left lung has two lobes. Most lung cancers start in the lining of the bronchi, the two tubes that lead to the lungs from the trachea, or windpipe.
The two main types of lung cancers are non-small-cell lung cancer and small-cell lung cancer. These types are diagnosed based on how the cells look under a microscope. Non-small-cell lung cancer, also termed squamous cell carcinoma, is the most common type of lung cancer and accounts for about 85 percent of lung cancers. The majority of these lung cancer patients have a history of smoking.
Each type of lung cancer has different kinds of cancer cells, and each type grows and spreads in different ways. The types of non-small-cell lung cancer are named for the kinds of cells found in the cancer and how they look under a microscope. Squamous cell carcinoma, also called epidermoid carcinoma, is a cancer that begins in the lining of the airways of the lung leading to the trachea, or windpipe. These cells are thin, flat cells that look like fish scales. Another type of lung cancer, large-cell carcinoma, may begin in several different types of large cells. Adenocarcinoma begins in the cells that line the air sacs in the lung, called alveoli, where oxygen and carbon dioxide gases are exchanged.
Small-cell cancer accounts for about 15 percent of all lung cancers. The most common type of small-cell cancer is oat cell cancer, in which the cells are small and oval in shape. Other small-cell lung cancers contain a combination of different small cells. When a lung cancer has characteristics of both small and non-small lung cancer cells, it is called a mixed small-cell/large-cell lung cancer.
Lung cancer treatment depends on many factors such as the exact tumor type (e.g. non-small-cell or small-cell lung cancer), the size, location, and extent of the tumor, the amount of underlying lung function and the patient’s general health. Several different treatments and combinations of treatments may be used to control lung cancers or to improve quality of life by reducing symptoms.
Common symptoms of lung cancer include a cough that gets worse over time; constant chest pain; coughing up blood; shortness of breath, wheezing, or hoarseness; repeated bouts of pneumonia or bronchitis; swelling of the neck and face; loss of appetite or weight loss; and fatigue.
As with all cancers, identifying the stage of lung cancer is essential for planning the best treatment. Several different tests may be done to help determine the stage, including chest x-ray and computed tomography (CT), which can provide details about the size and location of the tumor. Magnetic resonance imaging (MRI), positron emission tomography (PET) and bone scanning may also be done to determine if lung cancer has metastasized (spread to other parts of the body).
Small cell lung cancer is staged simply as either limited or extensive disease. Limited stage disease is defined as cancer in only one lung and in lymph nodes on the same side of the chest. With extensive stage disease, cancer cells are found in tissue in the chest outside of the lung with the tumor or in other organs, such as the liver or brain. In contrast, non-small cell lung cancer is classified according to the tumor, node, metastasis (TNM) system developed by the American Joint Committee on Cancer (AJCC). Oncologists who evaluate the results of imaging studies and pathologists who examine lung tissue obtained by biopsy or surgery categorize the tumor according to its size and location (T), whether cancer cells are found in nearby lymph nodes (N), and whether cancer has spread to other parts of the body (M). Once a lung cancer has been classified with the AJCC system, an overall stage is assigned to it.
Stages of Non-Small Cell Lung Cancer
| Stage |
Size, Location, and Spread of the Tumor |
TNM Staging According to AJCC System |
| Stage 0 |
Cancer cells are found only in the superficial inner lining of the lung |
Tis (carcinoma in situ) |
| Stage 1A |
The tumor is small and has grown through the superficial lining into deeper lung tissue |
T1, N0, M0
T1 = The tumor is 3 cm (1¼ inches) or less in size and has not extended beyond the lung
N0 = No cancer cells are found in nearby lymph nodes
M0 = There is no metastasis
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| Stage 1B |
The tumor is larger or has grown deeper
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T2, N0, M0
T2 = The tumor is one of the following:
Larger than 3 cm (1¼ inches)
Involves the main airway (bronchus)
Has invaded the pleura (the lining of the lung)
Is associated with collapsed lung tissue or swelling that
blocks part (but not all) of the lung
N0 = No cancer cells are found in nearby lymph nodes
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| Stage IIA |
The tumor is small but has grown deep; cancer cells are found in nearby lymph nodes
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T1, N1, M0
N1 = Cancer cells are found in lymph nodes within the lung, in the nearest lymph nodes around the airways, and/or in the hilum (a central area in the lung where blood and lymph vessels enter)
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| Stage IIB |
The tumor is larger and has invaded tissues beyond the lung; cancer cells may or may not be found in nearby lymph nodes
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T2, N1, M0
T3, N0, M0
T3 = The tumor has invaded any of the following:
Chest wall
Diaphragm (muscle separating the chest from the abdomen)
Pleura (sac surrounding the lungs)
Pericardium (outermost lining of the heart)
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| Stage IIIA |
The tumor may be any size, and cancer cells are found in the lymph nodes that are farther away from the lungs
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T1, T2, or T3, N2, M0
T3, N1, M0
N2 = Cancer cells are found in lymph nodes in the middle of the chest (between the two lungs) but on the same side of the chest as the lung tumor
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| Stage IIIB |
The tumor may be any size and cancer cells are found in nearby organs and lymph nodes that are farther away
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T4, Any N (0, 1, 2, or 3), M0
Any T, N3, M0
T4 = The tumor has invaded any of the following:
Mediastinum (breastbone)
Heart
Blood vessels that carry blood from the heart
Trachea or esophagus
Main portion of the spine
N3 = Cancer cells are found in lymph nodes in the middle of the chest (next to the opposite lung) or above the collar bone or in nearby or opposite muscle tissue
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| Stage IV |
Malignant growths are found in more than one lobe of the same lung or in the other lung or cancer cells are found in other parts of the body
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Any T, any N, M1
M1 = Metastasis has occurred
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Patients newly diagnosed with lung cancers are referred to specialists for treatment. Specialists who treat lung cancers include thoracic (chest) surgeons, medical oncologists, and radiation oncologists (see Finding Your Medical Team).
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