The National Lung Screening Trial was recently launched to find whether screening current and former smokers for lung cancer before they have symptoms can reduce deaths from this disease.

By February 2004, nearly 50,000 current or former smokers had joined NLST at more than 30 study sites across the country. The trial is now closed to further enrollment. If you would like more information about NLST, call the National Cancer Institute's Cancer Information Service toll-free, Monday through Friday, 9:00 a.m. to 4:30 p.m., at 1-800-4-CANCER (1-800-422-6237). Information is available in English or Spanish. The number for callers with TTY equipment is 1-800-332-8615.

If you are already enrolled in NLST, your continued participation through 2009 is critical to the success of the trial.

General NLST Questions
What is the National Lung Screening Trial?
What is the American Cancer Society’s role in NLST?
Why is the American Cancer Society supporting this trial versus others?
Why is this study needed?
What are the possible benefits of participating in this trial?
What are some of the possible risks of screening for lung cancer?
How long will the trial last? What will happen during the study?
Will taking part in NLST cost the participant anything?
What happens if lung cancer is found during the study?
What if a patient is underinsured or uninsured?
How can a potential participant or a physician get more information about lung cancer or NLST?

Science Related Questions
How does spiral CT work?
How is spiral CT used in hospitals now?
What is a randomized, controlled study?
Have current and former smokers participated in studies like this before?

General NLST Questions

The National Lung Screening Trial (NLST), a cancer screening clinical trial, compares two ways of detecting lung cancer: spiral computed tomography (CT) and standard chest x-ray. Both chest x-rays and spiral CT scans have been used to find lung cancer early. So far, however, neither method has definitively been shown to reduce a person's chance of dying from lung cancer. This study aims to show if one test is better than the other at reducing deaths from this disease.

By February 2004, nearly 50,000 current or former smokers had joined NLST at more than 30 study sites across the country. The trial, now closed to further enrollment, is slated to collect and analyze data for eight years, and will examine the risks and benefits of spiral CT scans compared to chest x-rays.

This trial is a randomized, controlled study–the "gold standard" of research studies–and is large enough to determine if there is a 20% or greater drop in lung cancer mortality from using spiral CT compared to chest x-ray.

The American Cancer Society's specific commitment is to help ensure that NLST reaches full enrollment quickly by supporting promotional and outreach efforts in those communities surrounding the local trial sites. The Society’s specific goal in this endeavor will be to increase general awareness and understanding of the trial so that potential participants and their physicians can make well-informed decisions about whether this trial is the right approach for them. In addition to creating formal promotion strategies and tactics, the national Society will ask for assistance from individual ACS Divisions in working to develop grassroots trial recruitment efforts where appropriate.

The NCI asked ACS for support on the NLST, and the Society then proposed to dedicate funds to help with recruitment. The bigger answer, however, is that this is one of the most important preventive health trials to take place in our lifetime, in that it is attempting to determine whether or not screening for lung cancer can reduce deaths. Lung cancer is the leading cause of cancer death in the world. Also, it has the potential to meet another important goal, which is strengthening relationships between Divisions and local cancer centers.

Lung cancer, which is most frequently caused by cigarette smoking, is the leading cause of cancer-related deaths in the United States. It claims more than 150,000 lives each year. Lung cancer kills more people than cancers of the breast, prostate, colon and pancreas combined. There are tens of millions of current and former smokers in the United States, all of whom are at high risk for lung cancer.

Currently, when lung cancer is detected, the disease has already spread outside the lung in more than half of all cases. Spiral CT, a technology introduced in the 1990s, can pick up tumors well under 1 centimeter in size, while chest x-rays detect tumors about one to two centimeters (0.4 to 0.8 inches) in size. Conventional wisdom suggests that the smaller the tumor, the more likely the chance of survival. But no scientific evidence to date has shown that screening or early detection of lung cancer actually saves lives. NLST, because of the number of individuals participating and because it is a randomized, controlled trial, will be able to provide the evidence needed to determine whether spiral CT scans are better than chest x-rays at reducing a person's chances of dying from lung cancer.

All participants will receive a free lung cancer screening exam. It is also possible that if lung cancer is detected, it may be caught at an early stage. Early detection of lung cancer may result in milder treatment with fewer side effects, or prolong life, but scientists don't know these things will happen for sure. Data gathered from NLST will help to clarify some of these uncertainties.

Recent studies indicate that 25% to 60%, or more, of screening spiral CT scans of smokers and former smokers will show abnormalities. Most of these abnormalities are not lung cancer. However, these abnormalities–scars from smoking, areas of inflammation, or other noncancerous conditions–can mimic lung cancer on scans and may require additional testing. These tests may cause anxiety for the participant or may lead to unnecessary biopsy or surgery.

Lung biopsy, a potentially risky procedure, involves the removal of a small amount of tissue, either through a scope fed down the windpipe (called bronchoscopy) or with a needle through the chest wall (called percutaneous lung biopsy). Though they happen infrequently, possible complications from biopsies include partial collapse of the lung, bleeding, infection, pain, and discomfort.

Depending upon the size and location of the abnormality detected, chest surgery (called thoracotomy or thoracic surgery) to obtain a larger biopsy specimen may be required. Thoracotomy is major surgery that removes substantial amounts of lung tissue. The procedure can damage nerves in the chest, and is more dangerous in people with underlying lung or heart conditions, which tend to be common in current or former smokers.

In addition, studies suggest that screening for lung cancer may detect small tumors that would never become life threatening. This phenomenon, called overdiagnosis, puts some screening recipients at risk from unnecessary biopsies or surgeries as well as unnecessary treatments for cancer, such as chemotherapy or radiation.

The study opened for enrollment in summer 2002. The researchers enrolled the 50,000 people for the trial study in less than 18 months. When people entered the study, they were randomized–assigned by chance–to receive either a spiral CT scan or a chest x-ray. These people will have the same screening procedure again one and two years later; they will be screened a total of three times. Until 2009, researchers will contact participants, by phone or mail, at least yearly to monitor their health.

Some NLST centers will collect blood, urine, or sputum (phlegm). These samples will be used for future research to test biomarkers that may someday help doctors better diagnose lung cancer.

During the trial, if participants want to quit smoking, they will be referred to smoking cessation resources. But they do not have to quit to take part in the study.

Participants will receive a free spiral CT scan or chest x-ray once a year for three years; however, costs for additional diagnostic evaluation or treatment for lung cancer or other medical conditions detected are not covered by the clinical trial. The clinical trial site can provide additional information regarding costs related to participation.

If a screening test reveals an abnormality that might be cancer, the study centers will recommend that participants speak with a physician regarding additional diagnostic tests and treatment. The clinical trial site can provide additional information regarding how diagnostic evaluations should be handled.

Efforts will be made wherever possible to ensure that diagnostic and therapeutic options are identified and referrals are made to appropriate sources to assist patients in obtaining care. The clinical trial site can provide additional information regarding how participants who are underinsured or uninsured can get appropriate care.

If you would like more information about NLST, call the National Cancer Institute's Cancer Information Service toll-free, Monday through Friday, 9:00 a.m. to 4:30 p.m., at 1-800-4-CANCER (1-800-422-6237). Information is available in English or Spanish. The number for callers with TTY equipment is 1-800-332-8615.

Spiral CT, also called helical CT, uses x-rays to scan the entire chest in about 15 to 25 seconds, during a single, large breath-hold. Throughout the procedure, the participant lies still on a table. The table and patient pass through the CT scanner, which is shaped like a donut with a large hole. The scanner rotates around the participant and a computer creates images from the scan, assembling them into a 2-D or 3-D model of the lungs.

More than half of the hospitals in the United States own a spiral CT machine. These machines are routinely used for staging lung and other cancers––that is, determining how advanced the cancer is after diagnosis. Recently some hospitals have begun performing spiral CT scans as a new way to find early lung cancer in smokers and former smokers, but their usefulness in this regard is still unknown.

A randomized, controlled trial is the most reliable method of determining what medical interventions work best and are safest. Participants are assigned by chance––randomized––to one of two groups, where one group receives one intervention and the other group receives another. One of the groups serves as a comparison group, or "control," for the other.

In a randomized trial, the goal is to determine if there are differences in outcomes between the two groups at the end of the study. The process of randomization aims to evenly distribute between the study groups all characteristics of the participants, such as health histories, that can influence outcome other than the interventions being studied.

If each group includes similar participants, then any differences seen in outcome between the two groups can be attributed to the intervention. In this screening study, participants will have an equal chance of being assigned to a group that is screened with spiral CT or to a group that is screened with chest x-ray.

To determine the willingness of participants to join a study like NLST, NCI launched a small trial, called the Lung Screening Study, to recruit 3,000 current and former smokers in late 2000. Within two months, all the necessary participants agreed to join the study and to be assigned by chance to receive either a spiral CT scan or a chest x-ray. The success of this study's recruitment led NCI to undertake NLST, which will be large enough to answer the important public health question of whether lung cancer screening with either of these two methods reduces deaths from the disease.