Key Clinical Updates in Screening for Lung Cancer
The USPSTF updated its recommendation for low-dose CT screening. Annual low-dose CT screening for lung cancer is recommended for those at high risk; with high-risk criteria including age 50-80 years, at least a 20 pack-years smoking history, and either current smoking or quit date within past 15 years. Screening should be stopped once 15 years have elapsed since quitting smoking, or if a comorbid condition renders the benefits of screening null. Simulation models developed for the purposes of informing this recommendation found yearly screening with this parameters to be the most efficient in reducing lung-cancer related deaths, although more false-positive test results are expected compared with the original recommendation.
Krist AH et al. JAMA. [PMID: 33687470]
Lung cancer remains the leading cause of cancer-related mortality, in large part secondary to advanced stage at diagnosis (Chapter 39). Two large RCTs reported findings in 2011 regarding the utility of lung cancer screening. The Prostate, Lung, Colorectal and Ovarian Randomized Trial (PLCO) randomized 154,901 adults (52% current or former smokers) between the ages of 55 and 74 years to receive either no screening or annual posterior-anterior chest radiographs for 4 consecutive years. The investigators monitored the participants after screening for an average of 12 years. Results showed no mortality benefit from four annual chest radiographs either in the whole cohort or in a subset of heavy smokers who met the entry criteria for the other major trial, the National Lung Screening Trial (NLST). The NLST enrolled 53,454 current or former smokers (minimum 30-pack year exposure history) between the ages of 55 and 74 years who were randomly assigned to one of two screening modalities: three annual posterior-anterior chest radiographs or three annual low-dose chest CT scans. They were monitored for an additional 6.5 years after screening. Compared with chest radiography, low-dose chest CT detected more early-stage lung cancers and fewer advanced-stage lung cancers, indicating that CT screening systematically shifted the time of diagnosis to earlier stages, thereby providing more persons the opportunity for effective treatment. Furthermore, compared with chest radiographs, the cohort that received three annual CT scans had a statistically significant mortality benefit, with reductions in both lung cancer deaths (20.0%) and all-cause mortality (6.7%). This was the first evidence from an RCT demonstrating that lung cancer screening reduced all-cause mortality.
Additional information from PLCO, the NLST, and multiple other ongoing randomized trials is available. Trials in the Netherlands and Belgium (NELSON), Germany (LUSI), Denmark (DLCST), the United Kingdom (UKLS), and Italy (MILD, DANTE, ITALUNG) have been completed. These have revealed variable findings depending on the risk profile of the included patients, but the broad results indicate that screening is most likely to be effective, with reduction in lung cancer-specific mortality, if performed at short intervals in a high-risk population, as was done in NLST. Some studies indicate that the mortality benefit may be higher among women than among men. Issues that remain ...