Lung Cancer

The lungs are part of the respiratory system. (Read about "Respiratory System") Our lungs let us take in oxygen, which is needed by all our cells. The lungs also expel the waste product carbon dioxide when we breathe out. Each lung has sections called lobes. A thin membrane called the pleura surrounds the lungs. Two tubes called bronchi lead from the trachea (windpipe) to the right and left lungs. The bronchi are sometimes involved in lung cancer. Small tubes called bronchioles and tiny air sacs called alveoli make up the inside of the lungs.

Of cancers that start in the lungs, there are two main types, according to the American Lung Association (ALA): non-small cell lung cancer and small cell lung cancer. Each type grows and spreads in different ways and is treated differently.

• Non-small cell lung cancer - ALA says non-small cell lung cancer is more common. It generally grows and spreads more slowly. There are three main types of non-small cell lung cancer:
  • squamous cell carcinoma (also called epidermoid carcinoma)
  • adenocarcinoma
  • large cell carcinoma

  For non-small cell lung cancer, the choice of treatment depends mainly on the size, location and extent of the tumor. Surgery is the most common way to treat this type of lung cancer. Cryosurgery, a treatment that freezes and destroys cancer tissue, may be used to control symptoms in the later stages of non-small cell lung cancer. Radiation therapy and chemotherapy may also be used to slow the progress of the disease and to manage symptoms. (Read about "Cancer Treatments")

• Small cell lung cancer - The National Cancer Institute (NCI) says that small cell lung cancer, sometimes called oat cell cancer, is less common than non-small cell lung cancer. Small cell lung cancer grows more quickly and is more likely to spread to other organs in the body. Because of this, when treating small cell lung cancer, NCI says doctors almost always use chemotherapy. Treatment may also include radiation therapy aimed at the tumor in the lung or tumors in other parts of the body, such as in the brain. Surgery is also part of the treatment plan for some patients with small cell lung cancer. (Read about "Cancer Treatments")

Causes and symptoms

Lung cancer is the leading cause of cancer deaths in the U.S. for both men and women, according to the National Cancer Institute (NCI). The American Lung Association (ALA) says that the rate of lung cancer has been dropping among men while the rate for women is increasing. According to the National Institutes of Health, tobacco is the key cause of lung cancer. Though not all cases of lung cancer are caused by smoking, many are. In fact, ALA says 87 percent of cases can be traced to tobacco use. It's not just cigarettes either. The American Cancer Society (ACS) says cigar and pipe smokers have a higher risk of lung cancer too. The number of years a person smokes, the amount smoked per day and how deeply the person inhales all affect the risk of developing lung cancer. In addition, ACS says the chance of developing lung cancer is increased by second-hand smoke, i.e. exposure to the smoke in the air when someone else smokes. ACS, ALA and NCI all agree the best way to avoid getting lung cancer is to quit smoking - or never start in the first place. (Read about "Quit Smoking")

There are other things that have been linked to lung cancer too, according to NCI:

• Radon is an invisible, odorless, and tasteless radioactive gas that occurs naturally in soil and rocks. People who work in mines can be exposed to radon; it can also be found inside the home. Radon can cause damage to the lungs that may lead to lung cancer.
• Asbestos fibers, used in certain industries, tend to break easily into particles. When the particles are inhaled, they can lodge in the lungs, damaging cells and increasing the risk for lung cancer. (Read about "Occupational Respiratory Diseases")
• Certain air pollutants that occur with the burning of diesel and other fossil fuels are being studied for a possible connection with an increase in the risk of lung cancer.
• Certain lung diseases, such as tuberculosis (TB), increase a person's chance of developing lung cancer. Lung cancer can develop in areas of the lung that are scarred from TB. (Read about "Tuberculosis")

Spotting the symptoms

Anyone who notices symptoms that can indicate the presence of lung cancer should see a doctor right away. The American Lung Association says these symptoms can include:

• persistent cough, especially coughing up blood
• persistent hoarseness
• chest pain
• shortness of breath and wheezing
• swelling of the neck and face
• loss of appetite or fatigue

These symptoms, of course, may also be caused by a number of other conditions such as pneumonia (Read about "Pneumonia"), so it's important to see a doctor as soon as possible for an examination and evaluation. (Read about "Cancer Check-ups")

Doctors can use several techniques to diagnose lung cancer, including imaging tests such as x-rays, PET scans, and magnetic resonance imaging. (Read about "X-rays" "PET - Positron Emission Tomography" "MRI - Magnetic Resonance Imaging") A technique called low-dose helical (or spiral) CT may also be used to help test for lung cancer. (Read about "CT Scan - Computerized Tomography") Bronchoscopy can also be used to look inside the trachea and large airways in the lung for abnormal areas and to take tissue samples for biopsy. (Read about "Endoscopy" "Biopsy")

If lung cancer is found, more tests will be done to find out if cancer cells have spread to other parts of the body. This is called staging. A doctor needs to know the stage of the disease to plan treatment. The following stages are used for lung cancer, according to NCI:

Non-small cell lung cancer

• Occult (hidden) stage

  In the occult (hidden) stage, cancer cells are found in sputum (mucus coughed up from the lungs), but no tumor can be found in the lung by imaging or bronchoscopy (Read about "Endoscopy"), or the primary tumor is too small to be assessed.

• Stage 0 (carcinoma in situ)

  In stage 0 (carcinoma in situ), cancer is limited to the lung and is found in a few layers of cells only. It has not grown through the top lining of the lung.

• Stage I

  In stage I, the cancer is in the lung only, with normal tissue around the tumor. Stage I is divided into stages IA and IB, based on the size of the tumor.

• Stage II

  In stage II, cancer has spread to nearby lymph nodes or to the chest wall (the ribs and muscles that make up the area of the body between the neck and the abdomen), the diaphragm (the thin muscle below the lungs and heart that separates the chest from the abdomen), the mediastinal pleura (the thin membrane that covers the outside of the lungs in the area near the heart), or the parietal pericardium (the outer layer of tissue that surrounds the heart). Stage II is divided into stage IIA and stage IIB, based on the size of the tumor and whether it has spread to the lymph nodes. (Read about "The Lymph System")

• Stage III

  In stage III, cancer has either:

  • spread to the lymph nodes in the mediastinum (the middle area between the lungs that contains the heart, major blood vessels, and other structures)
  • spread to the lymph nodes on the opposite side of the chest or in the lower neck.

  Stage III is divided into stage IIIA (which is sometimes treated with surgery) and stage IIIB (which is rarely treated with surgery).

• Stage IV

  In stage IV, cancer has spread to other parts of the body or to another lobe of the lungs.

Small cell lung cancer

• Limited Stage

  In limited stage, cancer is found in one lung, the tissues between the lungs, and nearby lymph nodes only. Lymph nodes are small, bean-shaped structures found throughout the body. They filter substances in a fluid called lymph and help fight infection and disease. (Read about "The Lymph System")

• Extensive Stage

  In extensive stage, cancer has spread outside of the lung where it began or to other parts of the body.

ACS says treatment options include:

• surgery to remove the tumor and some of the lung tissue around it. If a section of the lung is removed, the surgery is called a lobectomy; if the entire lung is removed, the surgery is called a pneumonectomy.
• chemotherapy, which can be used alone or in conjunction with other treatments
• radiation, which can also be used either alone or in combination with surgery and/or chemotherapy (Read about "Cancer Treatments")

Someone with lung cancer may also develop a condition called hypercalcemia - too much calcium in the blood - which in turn can cause loss of appetite, nausea, thirst, fatigue, muscle weakness, restlessness and confusion. This can often require medication and rehydration. (Read about "Hypercalcemia") Lung cancer can increase the risk of pneumothorax, a condition that can cause the lung to collapse. (Read about "Pneumothorax") Pleurisy - a painful inflammation of the lining of the lungs and chest cavity - can also develop. (Read about "Pleurisy")

More Cancer Information:

    Cancer Check-ups

    Cancer Support

    Cancer Treatments

    Reduce Cancer Risks

    Cancer Glossary

For a list of individual types of cancer, see Cancer: What It Is

Related Information:

    Respiratory System

    Glossary of Respiratory Terms