Screening with low dose CT scans significantly reduces lung cancer deaths

The National Cancer Institute released initial results from a large-scale clinical trial showing lung cancer screening with low-dose CT reduced mortality by 20% when compared to standard chest x-rays.

The National Cancer Institute (NCI) sponsored the National Lung Screening Trial, a randomized clinical trial, and randomly assigned 53,000 current and former heavy smokers to receive three annual screens with either low-dose CT or a standard chest x-ray.

“Everyone who participated in this trial has played an important role in providing hard evidence of a mortality benefit from CT screening for lung cancer as well as a road map for public policy development in the future,” said Dr. Denise Aberle, the national principal investigator for the trial, site co-principal investigator for the UCLA NLST team and a deputy chair of American College of Radiology Imaging Network (ACRIN).

The trial participants received their screening tests at enrollment and at the end of their first and second years on the trial. The participants were then followed for up to another five years; all deaths were documented, with special attention given to the verification of lung cancer as a cause of death.

On Oct. 20, a total of 354 deaths from lung cancer had occurred among participants in the CT arm of the study, whereas a significantly larger 442 lung cancer deaths had occurred among those in the chest x-ray group. The independent Data and Safety Monitoring Board concluded the 20.3% reduction in lung cancer mortality met the standard for statistical significance and recommended ending the study.

An ancillary finding showed that all-cause mortality was 7% lower in those screened with low-dose CT than in those screened with chest x-ray. Approximately 25% of deaths in the NLST were due to lung cancer, while other deaths were due to factors such as cardiovascular disease. Further analysis will be required to understand this aspect of the findings more fully.

“The main conclusion on the reduction of mortality due to lung cancer and the reduction of overall mortality constitute powerful evidence about the effectiveness of screening with helical CT,” said Constantine Gatsonis, PhD, the director of the ACRIN Biostatistics and Data Management Center, and professor of medical science and director of the Center for Statistical Sciences at Brown University.

In addition to collecting detailed information about the imaging screens and other clinical information, 15 NLST ACRIN sites collected and banked specimens of blood, sputum, and urine. Tissue of trial participants’ lung cancer was also collected across most sites. These specimens will provide a rich resource to validate molecular markers that may compliment imaging to detect early lung cancer.

The NLST ACRIN biospecimens were collected at the time of each of the three screening exams, said Aberle.

“There is major potential from these specimens to identify panels of genetic, protein and other molecular biomarkers of early lung cancer that can ultimately be translated into clinical practice,” she said.

The NLST results reported Nov. 4 are initial mortality findings and many more analyses will be completed in the coming months. Research topics include medical resource utilization for CT and chest x-ray screening, overall cost effectiveness of CT lung cancer screening, the affect of screening on an individual’s quality of life and what early biomarkers can be validated in the biospecimen archive.

A fuller analysis, with more detailed results, will be prepared for publication in a peer-reviewed journal within the next few months.