Lung cancer remains the most common cause of cancer-related death in men worldwide, and accounts for more deaths than prostate, colorectal, and pancreas combined. It is estimated that 90% of lung cancer deaths among men are due to smoking. Given the aggressive nature of lung cancer, there is a need for effective screening to detect early disease which is more responsive to treatment and potentially curable. Recently, the results of the National Lung Screening Trial* (NSLT) was published. The study examined whether screening with low-dose CT could reduce mortality from lung cancer. In this U.S. multicenter trial 53,454 persons at high risk for lung cancer were randomly assigned to undergo three annual screenings with either low-dose CT or single-view chest radiography. Eligible participants were between ages 55 and 74 and had a history of at least 30 pack-years; former smokers had quit within the previous 15 years. Data were compiled on cases of lung cancer and lung cancer deaths. A 20% decrease in lung cancer mortality was observed in the low-dose CT group as compared with the radiography group. The number needed to screen with low-dose CT to prevent one death from lung cancer was 320.
The research team of the trial concluded that the decrease in lung cancer mortality must be weighed against the harms related to false positive screening results, which include radiation exposure, psychological stress, and invasive diagnostic procedures for benign disease. The costs of the screening test and subsequent diagnostic evaluation also raises a significant concern. Currently, it is estimated that 7 million U.S. adults meet the entry criteria for the NLST, and 94 million U.S. adults are current or former smokers. A national screening program targeting either population would be very expensive.
Recently, the U.S. National Comprehensive Cancer Network (NCCN), released lung cancer screening guidelines. Based on the results of the NSLT, the NCCN recommends lung cancer screening with annual low-dose CT for patients who meet the NSLT inclusion criteria as stated above. Additional studies are necessary to help determine if low-dose CT should be recommended to all smokers.
Reference: The National Lung Screening Trial Research Team. Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening. N Engl J Med 2011;365:395-409.