617-732-NLST I pjudy@partners.org
What is NLST?
NLST, the National Lung Screening Trial, is an investigation sponsored by the National Cancer Institute and the American College of Radiology Image Network (ACRIN) for men and women at risk for lung cancer. The purpose of NLST is to determine whether lung-cancer screening using CT can reduce lung cancer mortality more than lung-cancer screening using the chest x-ray.
Status of National Lung Screening Trial at BWH
The National Lung Screen Trial at Brigham and Women's Hospital (BWH) closed to enrollment in January 2004, and on November 1, 2006, completed its last screening exam. Since September 5, 2002, when BWH enrolled the first of 540 participants, 1490 screening exams have been completed. However, the Trial is far from over. As of June 1, 2007, NLST at BWH has completed about 3500 questionnaires from participants about their encounters with medical care providers and about their smoking habits. By the time, the Trial is scheduled to end (sometime in 2010); BWH will send 3200 more follow-up questionnaires.
NLST is more than a trial to determine whether lung-cancer screening can reduce mortality. The Trial is collecting the questionnaire information so we will learn how to optimally diagnose and treat lung cancer. The Trial will determine how suspicious image findings should be followed. A suspicious image finding is usually a lung nodule that concerns the radiologist. The screening exam alone cannot determine reliably whether the nodule is a cancer or just a benign (non-cancerous) nodule. Lungs can contain small benign nodules and many physicians are concerned that CT is so sensitive that the numerous suspicious findings will overwhelm the medical care system.
NLST participants have had suspicious findings on their screening exams and the radiologists recommended follow-up examinations to participant's primary care physician. The follow-up process sometimes involved several examinations over time. The NLST Staff obtains the reports of those follow-up examinations so we can determine which follow-up examinations are effective.
Data Safety Monitoring Board
NLST might have important results before 2010 when the Trial is scheduled to end. Trial has an independent committee reviewing interim results called a Data Safety Monitoring Board (DSMB). How does a DSMB work? The DSMB evaluates interim results and can stop the Trial early because screening has been demonstrated to be effective earlier than planned. An early stopping of the Trial will be an important news story. If DSMB ends the Trial early, the Trial investigators would present the result to the participants and medical community. So we may not have to wait until 2010 to know whether lung cancer screening reduces mortality.
Evaluations of CT Screening Technology
The design of NLST involves continuing evaluations of lung-cancer screening technology. The NLST sites incorporated state-of-art imaging technology into the Trial as it became available at their site. The America College of Radiology Image Network (ACRIN), a sponsor of NLST, created a Physics Committee for the Trial. Philip F. Judy, Ph.D, the BWH site Principal Investigator, is a member of the Physics Committee. The Committee qualified the imaging devices at all Trial sites at the beginning of the Trial. However, qualifying imaging devices was on ongoing process because old equipment was replaced with state-of-the-art equipment. The Physics Committee created technique charts for each type of CT scanner. Technique charts indicate how the imaging device should be used to produce optimum screening exams. The Physics Committee established an image quality assurance program and reviewed the data from the quality assurance program. A quality assurance program is set of measurements performed at specified intervals that "assure" a consistent imaging performance. The procedures of ACRIN Physics Committee and results from the evaluations of the imaging devices have been published in a peer-reviewed journal. (Description and Implementation of a Quality Control Program in an Imaging-Based Clinical Trial, Christopher H. Cagnon, Dianna D. Cody, Michael F. McNitt-Gray, J. Anthony Seibert, Philip F. Judy, Denise R. Aberle, Academic Radiology: 2006; 13:1431-1441.) The procedures developed by the Physics Committee are likely to become the standards for quality assurance that will be necessary for all lung-cancer screening program should it be deemed to be effective by health policy makers. The history of mammography screening was that medical physicists developed quality assurance procedures during the mammography screening trials. Those procedures became the standard of practice, and now are Federal law now requires those quality assurance procedures to be used at all mammography facilities.
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