THE BENEFITS OF LOW DOSE CT LUNG CANCER SCREENING
Lung cancer is the leading cause of cancer death among both men and women. In fact, more people die each year from lung cancer than colon, breast, prostate and pancreatic cancer combined. And although many improvements in diagnosis, staging and treatment have been made, long-term lung cancer survival rates remain extremely poor.
The major risk factors, on the other hand, are well known. 90% of all lung cancer can be attributed to smoking. That means in the US, an estimated 94 million current or former smokers have an increased risk for the disease. The huge size of this at-risk group is a major reason why there have been many efforts to find and develop an effective low dose computed tomography (CT) lung cancer screening test over the past several years.
Recent Advances in Low Dose CT Lung Cancer Screening
In the past, efforts to identify an effective screening test have been unsuccessful. Specifically, several randomized screening trials were able to detect early-stage lung cancer, but were inconclusive in showing a mortality benefit from such screening. However, recent advances in multidetector computed tomography have allowed screening studies using low dose ct scan (LDCT) to be performed. With these tests, patients are exposed to acceptable levels of radiation and only need to hold a single breath. The low radiation dose preserves the detection of focal lung lesions because of the inherently high contrast between aerated lung and soft tissue.
National Lung Screening Trial (NLST)
The question the NLST set out to answer was whether low dose CT lung cancer screening would reduce mortality from lung cancer for high-risk individuals. The NLST focused on screening people 55 to 74 years old who have cigarette smoking histories of 30 or more pack-years, and who, if they are former smokers, have quit within the last 15 years.
The initial NLST found that screening with low dose CT scan reduces mortality by 20% and all-cause mortality by 6.7%.
NLST Results (excerpt)
Lung cancer mortality reduction: 20%
(95% confidence interval [CI], 6.8–26.7; P = .004)
All-cause mortality reduction: 6.7%
(95% CI, 1.2–13.5; P = .02)
Study Design: Evidence obtained from a randomized controlled trial.
Internal Validity: Good
Consistency: Not applicaable (N/A) – one randomized trial to date.
External Validity: Fair
With these results, the NLST trial is the first randomized screening trial for lung cancer to have shown improvements in both disease-specific and all-cause mortality.
Despite being the number one cause of cancer death, lung cancer isn’t the most heavily researched. In fact, federal funding for lung cancer research is relatively small compared with funding for other major cancers. That’s why, with this clear conclusion that low dose CT lung cancer screening reduces mortality by up to 20%, the NLST is a major step forward in the advancement of more effective lung cancer screening programs. By increasing detection of this potentially-curable disease, low dose CT lung cancer screening can drastically change lung cancer examination and management for hospitals and patients across the country.
Gutierrez A, Suh R, Abtin F, Genshaft S, Brown K. Lung Cancer Screening. NCBI Website. Accessed October 16, 2018.
Lung Cancer Screening (PDQ) – Health Professional Version. National Cancer Institute Website. Accessed October 16, 2018.