Patients screened with low-dose helical CT (computed tomography) have a 20% lower risk of dying from lung cancer compared to those screened with chest X-rays, researchers reported in the New England Journal of Medicine (NEJM). The authors revealed their findings from NLST (National Lung Screening Trial), involving 53,000 individuals who either smoked heavily during the trial or used to do so.

With over 94 million current or ex-smokers in the USA, lung cancer is the country's leading cause of cancer-related deaths. In the majority of cases, when lung cancer is diagnosed, it has already advanced and is very difficult to cure.

Denise R. Aberle, M.D., 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 study, which lasted nearly ten years, enrolled individuals for 20 months. They were randomly assigned to receive three annual screenings, either with standard chest X-ray or low-dose helical CT. The trial was sponsored by the National Cancer Institute, part of the NIH (National Institutes of Health).

Principal researcher, .William C. Black, MD, said:

"During the screening phase of the trial, 39.1% of participants in the low-dose helical CT arm and 16.0% 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% of the low-dose helical CT and 94.5% of the chest X-ray examinations were false-positive.

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 authors explained that in most cases the false-positive results were likely due to normal lymph node or inflamed tissue detection.

There were relatively few events in the National Lung Screening Trial. Fewer than 2% of patients experienced complications as a result of the diagnostic evaluations prompted by a positive screening.

Researcher, Constantine Gatsonis, Ph.D., said:

"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 trials using NLST data should be carried out, the authors add. These should include the use of statistical modeling to better determine patient risk profiles.

Gatsonis stressed:

"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."

Blood, sputum and urine specimens as well as samples of early-stage lung cancer were collected at the American College of Radiology Imaging Network sites and banked in the NILST-ACRIN Biorepository. These samples are available to outside researchers.

Aberle said:

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

Fellow researcher, Mitchell D. Schnall, M.D., Ph.D., 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.

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."

"Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening"
The National Lung Screening Trial Research Team
NEJMJune 29, 2011 (10.1056/NEJMoa1102873)