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.

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.