The results of a lung cancer screening clinical trial were so dramatic that the National Cancer Institute (NCI) decided to end the study early in order to inform the public of the outcome. Researchers working on NCI’s National Lung Screening Trial (NLST) noted a reduction of 20 percent in lung cancer deaths when smokers and former smokers underwent CT screening instead of chest X-rays.
Within the last decade, using CT imaging to screen current and former smokers for lung cancer – the leading cancer killer in the United States – has been debated within the medical and health insurance communities. Early studies were inconclusive when it came to finding early lung cancer using this technology.
Just as criticism arose over the usefulness of annual screening mammograms for women, the use of CT scans to detect malignancies in the lungs of tobacco smokers has proven controversial. Detractors have pointed to risks from radiation exposure after repeated scans. These studies are also expensive, averaging around $300 each, according to The Washington Post.
The NLST was a cancer screening clinical trial launched in 2002. The objective of the study was to compare the effects of two methods of detecting lung cancer on mortality rates for the disease. The two techniques targeted were standard chest X-rays and low-dose helial CT scans, both of which have been previously used to try to find lung cancer in its earliest stages.
The trial studied more than 53,000 current or former heavy smokers over a period of 20 months. Subjects ranged in age from 55 to 74 and participated at 33 sites across the U.S. The independent group monitoring data from the study decided that by October of 2010, the trial had yielded statistically significant data that NCI should make public.
NLST researchers reported 20 percent fewer lung cancer deaths among the subjects who underwent CT screening than those experienced by individuals screened by standard chest X-rays. Scientists were also surprised to find that overall, the mortality rate from all causes was seven percent lower for those who underwent the CT screening. All subjects were screened three times during their participation in the trial. Many were followed for as long as five years.
According to the NCI, the results applied to a high-risk group of patients and don’t suggest that everyone should undergo regular CT screening for lung cancer. The agency further states that the risk of regular screens could be considerable, especially for individuals who are healthy.
Scientists also undertook an analysis of 30,000 patients who participated in a study that began in 1992. These subjects had a similar smoking history as individuals in the NLST and were also similar in age. The results showed no benefits in the death rate when the screening technique used was a standard chest X-ray.
NCI stresses that the results from this trial regarding lung cancer mortality rates were only initial findings. Dozens of questions surrounding the implications still need to be addressed.
Among the most important is how a finding of lung cancer after screening affects a patient’s overall quality of life. Experts also want to determine how this type of screening will influence beliefs about smoking as well as smoking behavior. They also cite the need to figure out how cost-effective CT screening will prove to be.
Researchers remain unclear as to why the trial yielded a seven percent reduction of deaths from any cause. The most popular theory is that screening using CT scans revealed other types of cancer or illnesses.
The goal of any type of lung cancer screening is to catch the disease in its early stages, when doctors consider it the most treatable. However, experts are quick to admit that results of the $250 million NLST require more analysis in order to determine exactly who might benefit from CT screening for lung cancer and how often they need to be screened.