Study Finds Annual Low-Dose CT Screening Effective in Identifying Precancerous Lung Nodules
A large international prospective study investigating the safety and effectiveness of using annual low-dose computed tomography (CT) as a screening tool to monitor nonsolid lung nodules has found that CT was accurate in identifying nodules that were likely to become cancerous. The study also found that the transition time from nonsolid to part-solid nodules was more than 2 years, suggesting that nonsolid nodules of any size can be safely followed with CT at 12-month intervals to assess a potential transition to part-solid nodules, reducing the need for unnecessary tests and surgery. The study by Yankelevitz et al is published in Radiology.
Study Methodology
The researchers analyzed CT screening data from 57,496 participants in the International Early Lung Cancer Program (I-ELCAP). The data included baseline and annual repeat screenings performed between January 1, 2001, and December 31, 2013. A nonsolid nodule was defined as a nodule that does not obscure the underlying lung parenchyma and in which the only solid components are blood and vessels, identified by their branching structure. A nonsolid nodule was considered to have grown if it increased in its overall size or developed solid components.
Study Findings
The study found that a nonsolid nodule was identified in 2,392 (4.2%) baseline low-dose CT screenings, and further pathologic analysis led to a diagnosis of adenocarcinoma in 73 cases. A new nonsolid nodule was identified in 485 (0.7%) of 64,677 annual repeat screenings, and 11 had a diagnosis of stage I adenocarcinoma; none was in nodules 15 mm or larger in diameter. Nonsolid nodules resolved or decreased more frequently in annual repeat than in baseline rounds (322 [66%] of 485 vs 628 [26%] of 2392, P < .0001).
Treatment of the cases of lung cancer was lobectomy in 55, bilobectomy in 2, sublobar resection in 26, and radiation therapy in 1. Median time to treatment was 19 months (interquartile range [IQR] = 6–41 months). A solid component had developed in 22 cases prior to treatment (median transition time from nonsolid to part-solid was 25 months). The lung cancer survival rate was 100%, with median follow-up since diagnosis of 78 months (IQR = 45–122 months).
Shared Decision-Making Between Physician and Patient
“Our findings support the safety of annual repeat scans for individuals with only nonsolid nodules and that pathologic diagnosis should be pursued only when a solid component develops. Earlier treatment of these cancers when they were either small or had not yet developed a solid component would have provided no additional benefit. However, in light of the many factors to be considered for these challenging nodules, this report highlights the need for shared decision-making, which is considered an essential and well-accepted component of all screening programs,” concluded the study authors.
Claudia L. Henschke, MD, PhD, of the Icahn School of Medicine at Mount Sinai, is the corresponding author of this study.
Funding for this study was provided by the National Institutes of Health. For full disclosures of the study authors, visit radiology.rsna.org.
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