A new study, titled ‘National Lung Screening Trial’ (NLST), conducted by the American College of Radiology Imaging Network (ACRIN) and the National Cancer Institute’s Lung Screening Study Group, has shown a twenty percent decline in mortality due to lung cancer among study participants who were screened with low-dose helical computed tomography (CT) compared to those screened with chest X-ray. The results of the study were recently published online in the New England Journal of Medicine. Both former and current heavy smokers were allowed to participate in the research study.

Lung cancer is a disease that consists of uncontrolled cell growth in tissues of the lung. It is one of the most common causes of cancer related deaths in the United States, with an estimated 94 million existing or past smokers who are at high risk of developing the disease. To make matters worse, in most cases the disease is identified only when it is at an advanced stage and less likely to be curable as the symptoms do not present until then.

Dr. Denise R. Aberle, M.D., who serves as the national principal investigator for NLST ACRIN, a deputy co-chair of ACRIN, professor of radiology and bioengineering and vice chair for research in Radiological Sciences at UCLA said:

“The trial results provide hard evidence of the mortality benefit from low-dose helical CT screening for lung cancer in an older and heavy smoker population. These findings, and the vast amount of additional data generated by the NLST that are still being studied, offer a rich resource of information that will inform the development of clinical guidelines and policy recommendations.”

The National Cancer Institute (NCI), which is a part of the National Institutes of Health (NIH), was the sponsor for this lengthy study that enrolled a total of 53,000 subjects across 33 study centers over a period of 20 months in the United States. The participants were assigned randomly to obtain three annual screening examinations, with either a standard chest X-ray or a low-dose helical CT.

The valuable details provided in the research paper were about the number of study participants that identified a abnormalities possibly linked to cancer and the number of abnormalities that were actually found out to be cancer. The researchers stated:

“During the screening phase of the trial, 39.1 percent of participants in the low-dose helical CT arm and 16.0 percent of those in the chest X-ray arm had a positive screening result. Across all three screening examination rounds, when a positive result was found, 96.4 percent of the low-dose helical CT and 94.5 percent of the chest X-ray examinations were false-positive.”

Dr. William C. Black, MD, chair of the ACRIN Outcomes and Economics Committee and NLST site principal investigator at Dartmouth-Hitchcock Medical Center said:

“The follow-up for positive screening examinations most frequently involved further imaging tests and the data show that follow-up with invasive procedures was uncommon. We also found that lower rates of follow-up resulting from a positive scan occurred at later screening rounds.”

The majority of false-positive results were due to the detection of inflamed tissues and normal lymph nodes.

In the National Lung Screening Trial there were relatively few and minor adverse events (harms resulting from the actual screening examinations) reported. A two percent or less rate of complication among those participants who underwent a diagnostic evaluation for either type of screening was reported.

Dr. Constantine Gatsonis, Ph.D., the director of the ACRIN Biostatistics and Data Management Center, and chair of biostatistics in the public health program of the Warren Alpert Medical School of Brown University commented:

“Although the NLST provides definitive evidence about the effectiveness of low-dose helical CT screening for lung cancer, significant further work is required to answer questions critical for the development of public policy recommendations.”

Further studies based on the data obtained from the NLST that would include the use of statistical modeling are required. These would provide significant information regarding the risk profiles of patients, screening regimens and positive screen criteria resulting in the maximum benefit from screening.

To further emphasize this, Dr. Gatsonis stated:

“Given the considerable costs associated with low-dose helical CT screening, a cost-effectiveness analysis using the NLST data is underway that will guide decisions about the best use of finite health care resources.”

A unique opportunity for early detection of lung cancer by advancing investigation of molecular biomarkers was provided by the NLST. After obtaining informed consent from NLST participants, specimens such as blood, sputum, urine, and of early stage lung cancer were obtained and collected at ACRIN sites. These samples are banked in the NLST-ACRIN Bio repository and are available to the larger research community.

Dr. Denise R. Aberle said:

“These specimens provide a rich resource to validate molecular markers that may complement imaging to detect early lung cancer. By coupling bio specimen collection with imaging-based screening, the NLST-ACRIN Bio repository is relatively enriched for early clinical-stage lung cancers and associated bio specimens, and provides a unique resource of extremely well-characterized bio specimens with longitudinal data.”

Dr. Mitchell D. Schnall, M.D., Ph.D., ACRIN’s network chair and Matthew J. Wilson Professor of Research Radiology at the University of Pennsylvania, said:

“The knowledge that low-dose CT is a viable screening tool for detecting lung cancers at a curable stage is a tremendous first step for better understanding its implications for clinical care. Working with the Eastern Cooperative Oncology Group through the recently announced alliance, will allow us to extend these significant results to answer future questions critical for translating today’s findings into clinical practice.”

The authors conclude:

“Furthermore, ACRIN is engaged in a research project with Boston University funded by the United States Department of Defense to investigate the role of blood and sputum-based laboratory tests to better define patient populations who would most benefit from lung cancer screening and, thereby, reducing false-positive screenings.”

Source: American College of Radiology

Written by Barry Windsor