April 2024
Twenty-year follow-up of lung cancer screening by CT

In an observational study, estimated 10-year and 20-year lung cancer-free survival were both 81%.

The International Early Lung Cancer Action Project (I­ELCAP) is a non­ randomised study in which smokers were screened with annual low­dose computed tomography (CT). The study began in 1992, and in a previous report, estimated lung cancer­ specific 10-­year survival was 80% among participants diagnosed with lung cancer (NEJM JW Oncol Hematol Feb 2007 and N Engl J Med 2006; 355: 1763-­1771).

Now, the researchers have reported even longer follow up. Lung cancer was diagnosed in 1.4% of 89,000 participants (median age, 66 years; median smoking history, 43 pack­-years), and 81% of those cases were clinical stage 1. Estimated 10­-year and 20-year lung cancer-­specific survival were both 81%. In the subgroup with pathological stage T1aN0M0, 20-­year lung cancer-­specific survival was 95%.

Comment: These findings are worth sharing with patients in whom CT screening detects early­stage lung cancer. The 81% lung cancer-specific survival seen at 10 years was maintained during a second decade of follow up, suggesting that most screen-detected, treated patients had long-term cure. Smoking cessation in treated patients might partially explain this outcome (by lowering risk for later-onset, second cancers). Although this study has the usual limitations of observational screening studies (e.g. lead-time and length-time biases; overdiagnosis), the results largely align with findings from randomised trials, and the extended follow up is the longest reported for any cohort of CT-screened smokers.

Allan S. Brett, MD, Clinical Professor of Medicine, University of Colorado School of Medicine, Aurora, USA.

Henschke CI, et al. A 20-year follow-up of the International Early Lung Cancer Action Program (I-ELCAP). Radiology 2023; 309: e231988.

This summary is taken from the following Journal Watch titles: General Medicine, Oncology and Hematology.