What is screening?
General Information About Lung Cancer
Lung Cancer Screening
Risks of Lung Cancer Screening
Get More Information From NCI
Changes to This Summary (02/17/2006)
Questions or Comments About This Summary
About PDQ

What is screening?

Screening is looking for cancer before a person has any symptoms. This can help find cancer at an early stage. When abnormal tissue or cancer is found early, it may be easier to treat. By the time symptoms appear, cancer may have begun to spread.

Scientists are trying to better understand which people are more likely to get certain types of cancer. They also study the things we do and the things around us to see if they cause cancer. This information helps doctors recommend who should be screened for cancer, which screening tests should be used, and how often the tests should be done.

It is important to remember that your doctor does not necessarily think you have cancer if he or she suggests a screening test. Screening tests are given when you have no cancer symptoms.

If a screening test result is abnormal, you may need to have more tests done to find out if you have cancer. These are called diagnostic tests.

Refer to the following PDQ summaries for information about prevention, diagnosis, and treatment of lung cancer:

• Prevention of Lung Cancer ¹
• Non-Small Cell Lung Cancer Treatment ²
• Small Cell Lung Cancer Treatment ³

General Information About Lung Cancer

Key Points for This Section

Lung cancer is a disease in which malignant (cancer) cells form in the tissues of the lung. Lung cancer is the leading cause of cancer death in the United States. Tobacco smoking is the most important risk factor for lung cancer.

Lung cancer is a disease in which malignant (cancer) cells form in the tissues of the lung.

The lungs are a pair of cone-shaped breathing organs inside the chest. The lungs bring oxygen into the body when breathing in and send carbon dioxide out of the body when breathing out. Each lung has sections called lobes. The left lung has two lobes. The right lung, which is slightly larger, has three. 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.

There are two types of lung cancer: small cell lung cancer and non-small cell lung cancer.

Lung cancer is the leading cause of cancer death in the United States.

Lung cancer is the leading cause of cancer death and the second most common nonskin cancer in the United States.

Tobacco smoking is the most important risk factor for lung cancer.

Anything that increases a person's chance of developing a disease is called a risk factor. The main cause of lung cancer is tobacco use, including smoking cigarettes, cigars, or pipes, now or in the past.

There are other risk factors for lung cancer, but even when taken together, their effect on lung cancer is very small compared to the effect of tobacco smoking. These include the following:

• Being exposed to second-hand smoke.
• Being exposed to asbestos, arsenic, chromium, nickel, or other workplace agents.
• Being exposed to radon, which can be found in the home as well as in the workplace.

Lung Cancer Screening

Key Points for This Section

Tests are used to screen for different types of cancer. Two tests have commonly been used to screen for lung cancer. Chest x-ray Sputum cytology New tests are being studied in clinical trials. Spiral CT scan

Tests are used to screen for different types of cancer.

Some screening tests are used because they have been shown to be helpful both in finding cancers early and decreasing the chance of dying from these cancers. Other tests are used because they have been shown to find cancer in some people; however, it has not been proven in clinical trials that use of these tests will decrease the risk of dying from cancer.

Scientists study screening tests to find those with the fewest risks and most benefits. Cancer screening trials also are meant to show whether early detection (finding cancer before it causes symptoms) decreases a person's chance of dying from the disease. For some types of cancer, finding and treating the disease at an early stage may result in a better chance of recovery.

Clinical trials that study cancer screening methods are taking place in many parts of the country. Information about ongoing clinical trials is available from the NCI Cancer.gov Web site ⁴.

Two tests have commonly been used to screen for lung cancer.

It has not yet been shown that screening for lung cancer with either of the following tests decreases the chance of dying from lung cancer:

Chest x-ray

A chest x-ray is an x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.

Sputum cytology

Sputum cytology is a procedure in which a sample of sputum (mucus that is brought up from the lungs by coughing) is viewed under a microscope to check for cancer cells.

New tests are being studied in clinical trials.

Spiral CT scan

Spiral CT scan is a procedure that makes a series of very detailed pictures of areas inside the body using an x-ray machine that scans the body in a spiral path. The pictures are made by a computer linked to the x-ray machine. This procedure is also called a helical CT scan.

Screening clinical trials are taking place in many parts of the country. Information about NCI's lung screening trial can be found at the National Lung Screening Trial (NLST) Web site. ⁵ Information about other clinical trials is available from the NCI Cancer.gov Web site ⁴.

Risks of Lung Cancer Screening

Key Points for This Section

Screening tests have risks. The risks of lung cancer screening tests include the following: Finding lung cancer may not improve health or help you live longer. False-negative test results can occur. False-positive test results can occur. Chest x-rays expose the chest to radiation. Your doctor can advise you about your risk for lung cancer and your need for screening tests.

Screening tests have risks.

Decisions about screening tests can be difficult. Not all screening tests are helpful and most have risks. Before having any screening test, you may want to discuss the test with your doctor. It is important to know the risks of the test and whether it has been proven to reduce the risk of dying from cancer.

The risks of lung cancer screening tests include the following:

Finding lung cancer may not improve health or help you live longer.

Screening may not improve your health or help you live longer if you have advanced lung cancer or if it has already spread to other places in your body.

Some cancers never cause symptoms or become life-threatening, but if found by a screening test, the cancer may be treated. It is not known if treatment of these cancers would help you live longer than if no treatment were given, and treatments for cancer may have serious side effects.

False-negative test results can occur.

Screening test results may appear to be normal even though lung cancer is present. A person who receives a false-negative test result (one that shows there is no cancer when there really is) may delay seeking medical care even if there are symptoms.

False-positive test results can occur.

Screening test results may appear to be abnormal even though no cancer is present. A false-positive test result (one that shows there is cancer when there really isn't) can cause anxiety and is usually followed by more tests (such as biopsy), which also have risks. A biopsy to diagnose lung cancer can cause part of the lung to collapse. Sometimes surgery is needed to reinflate the lung.

Chest x-rays expose the chest to radiation.

Radiation exposure from chest x-rays may increase the risk of developing certain cancers, such as breast cancer.

Your doctor can advise you about your risk for lung cancer and your need for screening tests.

Get More Information From NCI

Call 1-800-4-CANCER

For more information, U.S. residents may call the National Cancer Institute's (NCI's) Cancer Information Service toll-free at 1-800-4-CANCER (1-800-422-6237) Monday through Friday from 9:00 a.m. to 4:30 p.m. Deaf and hard-of-hearing callers with TTY equipment may call 1-800-332-8615. The call is free and a trained Cancer Information Specialist is available to answer your questions.

Chat online

The NCI's LiveHelp® ⁶ online chat service provides Internet users with the ability to chat online with an Information Specialist. The service is available from 9:00 a.m. to 11:00 p.m. Eastern time, Monday through Friday. Information Specialists can help Internet users find information on NCI Web sites and answer questions about cancer.

Write to us

For more information from the NCI, please write to this address:

NCI Public Inquiries Office

Suite 3036A

6116 Executive Boulevard, MSC8322

Bethesda, MD 20892-8322

Search the NCI Web site

The NCI Web site ⁷ provides online access to information on cancer, clinical trials, and other Web sites and organizations that offer support and resources for cancer patients and their families. For a quick search, use our “Best Bets” search box in the upper right hand corner of each Web page. The results that are most closely related to your search term will be listed as Best Bets at the top of the list of search results.

There are also many other places to get materials and information about cancer treatment and services. Hospitals in your area may have information about local and regional agencies that have information on finances, getting to and from treatment, receiving care at home, and dealing with problems related to cancer treatment.

Find Publications

The NCI has booklets and other materials for patients, health professionals, and the public. These publications discuss types of cancer, methods of cancer treatment, coping with cancer, and clinical trials. Some publications provide information on tests for cancer, cancer causes and prevention, cancer statistics, and NCI research activities. NCI materials on these and other topics may be ordered online or printed directly from the NCI Publications Locator ⁸. These materials can also be ordered by telephone from the Cancer Information Service toll-free at 1-800-4-CANCER (1-800-422-6237), TTY at 1-800-332-8615.

Changes to This Summary (02/17/2006)

The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.

Changes were made to this summary to match those made to the health professional version.

Questions or Comments About This Summary

If you have questions or comments about this summary, please send them to Cancer.gov through the Web site’s Contact Form ⁹. We can respond only to email messages written in English.

About PDQ

PDQ is a comprehensive cancer database available on NCI's Web site.

PDQ is the National Cancer Institute's (NCI's) comprehensive cancer information database. Most of the information contained in PDQ is available online at NCI's Web site ⁷. PDQ is provided as a service of the NCI. The NCI is part of the National Institutes of Health, the federal government's focal point for biomedical research.

PDQ contains cancer information summaries.

The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries are available in two versions. The health professional versions provide detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions provide current and accurate cancer information.

The PDQ cancer information summaries are developed by cancer experts and reviewed regularly.

Editorial Boards made up of experts in oncology and related specialties are responsible for writing and maintaining the cancer information summaries. The summaries are reviewed regularly and changes are made as new information becomes available. The date on each summary ("Date Last Modified") indicates the time of the most recent change.

PDQ also contains information on clinical trials.

A clinical trial is a study to answer a scientific question, such as whether a method of finding cancer earlier can help people to live longer. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients and those who are at risk for cancer. During screening clinical trials, information is collected about the effects of a new screening method and how well it works. If a clinical trial shows that a new method is better than one currently being used, the new method may become "standard." People who are at high risk for a certain type of cancer may want to think about taking part in a clinical trial.

Listings of clinical trials are included in PDQ and are available online at NCI's Web site ¹⁰. Descriptions of the trials are available in health professional and patient versions. Many cancer doctors who take part in clinical trials are also listed in PDQ. For more information, call the Cancer Information Service 1-800-4-CANCER (1-800-422-6237); TTY at 1-800-332-8615.

Glossary Terms

Not normal. An abnormal lesion or growth may be cancerous, premalignant (likely to become cancer), or benign.

Tiny air sacs at the end of the bronchioles in the lungs.

A poisonous chemical used to kill weeds and pests. Also used in cancer therapy.

A group of minerals that take the form of tiny fibers. Asbestos has been used as insulation against heat and fire in buildings. Loose asbestos fibers breathed into the lungs can cause several serious diseases, including lung cancer and malignant mesothelioma (cancer found in the lining of the lungs, chest, or abdomen). Asbestos that is swallowed may cause cancer of the gastrointestinal tract.

The removal of cells or tissues for examination by a pathologist. The pathologist may study the tissue under a microscope or perform other tests on the cells or tissue. There are many different types of biopsy procedures. The most common types include: (1) incisional biopsy, in which only a sample of tissue is removed; (2) excisional biopsy, in which an entire lump or suspicious area is removed; and (3) needle biopsy, in which a sample of tissue or fluid is removed with a needle. When a wide needle is used, the procedure is called a core biopsy. When a thin needle is used, the procedure is called a fine-needle aspiration biopsy.

The large air passages that lead from the trachea (windpipe) to the lungs.

A tiny branch of air tubes in the lungs.

A term for diseases in which abnormal cells divide without control. Cancer cells can invade nearby tissues and can spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord.

The individual unit that makes up the tissues of the body. All living things are made up of one or more cells.

An x-ray of the structures inside the chest. An x-ray is a type of high-energy radiation that can go through the body and onto film, making pictures of areas inside the chest, which can be used to diagnose disease.

A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease. Also called a clinical study.

The process of identifying a disease, such as cancer, from its signs and symptoms.

A method used to identify a disease.

A test result that indicates that a person does not have a specific disease or condition when the person actually does have the disease or condition.

A test result that indicates that a person has a specific disease or condition when the person actually does not have the disease or condition.

A portion of an organ, such as the liver, lung, breast, thyroid, or brain.

One of a pair of organs in the chest that supplies the body with oxygen, and removes carbon dioxide from the body.

A thick, slippery fluid made by the membranes that line certain organs of the body, including the nose, mouth, throat, and vagina.

A group of lung cancers that are named for the kinds of cells found in the cancer and how the cells look under a microscope. The three main types of non-small cell lung cancer are squamous cell carcinoma, large cell carcinoma, and adenocarcinoma. Non-small cell lung cancer is the most common kind of lung cancer.

A part of the body that performs a specific function. For example, the heart is an organ.

A thin layer of tissue that covers the lungs and lines the interior wall of the chest cavity. It protects and cushions the lungs. This tissue secretes a small amount of fluid that acts as a lubricant, allowing the lungs to move smoothly in the chest cavity while breathing.

Energy released in the form of particle or electromagnetic waves. Common sources of radiation include radon gas, cosmic rays from outer space, medical x-rays, and energy given off by a radioisotope (unstable form of a chemical element that releases radiation as it breaks down and becomes more stable).

A radioactive gas that is released by uranium, a substance found in soil and rock. Breathing in too much radon can damage lung cells and may lead to lung cancer.

Something that may increase the chance of developing a disease. Some examples of risk factors for cancer include age, a family history of certain cancers, use of tobacco products, certain eating habits, obesity, lack of exercise, exposure to radiation or other cancer-causing agents, and certain genetic changes.

Checking for disease when there are no symptoms. Since screening may find diseases at an early stage, there may be a better chance of curing the disease. Examples of cancer screening tests are the mammogram (breast), colonoscopy (colon), Pap smear (cervix), and PSA blood level and digital rectal exam (prostate). Screening can also include checking for a person’s risk of developing an inherited disease by doing a genetic test.

A problem that occurs when treatment affects healthy tissues or organs. Some common side effects of cancer treatment are fatigue, pain, nausea, vomiting, decreased blood cell counts, hair loss, and mouth sores.

An aggressive (fast-growing) cancer that forms in tissues of the lung and can spread to other parts of the body. The cancer cells look small and oval-shaped when looked at under a microscope.

A detailed picture of areas inside the body. The pictures are created by a computer linked to an x-ray machine that scans the body in a spiral path. Also called helical computed tomography.

Mucus and other matter brought up from the lungs by coughing.

Examination under a microscope of cells found in sputum (mucus and other matter brought up from the lungs by coughing). The test checks for abnormal cells, such as lung cancer cells.

The extent of a cancer in the body. Staging is usually based on the size of the tumor, whether lymph nodes contain cancer, and whether the cancer has spread from the original site to other parts of the body.

A procedure to remove or repair a part of the body or to find out whether disease is present. An operation.

An indication that a person has a condition or disease. Some examples of symptoms are headache, fever, fatigue, nausea, vomiting, and pain.

A group or layer of cells that work together to perform a specific function.

The airway that leads from the larynx (voice box) to the bronchi (large airways that lead to the lungs). Also called windpipe.

A type of high-energy radiation. In low doses, x-rays are used to diagnose diseases by making pictures of the inside of the body. In high doses, x-rays are used to treat cancer.