Screen-detected Lung Cancer: A Retrospective Analysis of CT Appearance

Rationale and Objectives: The aim of this study was to retrospectively evaluate characteristics of lung cancers diagnosed in a low-dose computed tomographic lung cancer screening study. Materials and Methods: As part of the International Early Lung Cancer Action Program, a cohort of 4782 at-risk participants were screened. A total of 86 cancers in 84 individuals were detected and evaluated for location, morphology (density, border), size, histology, stage at diagnosis, treatment, and survival. Follow-up imaging for computation of growth rates was available in 41 cases. Results: Eighty-six cancers were detected in 84 individuals (60 women, 24 men). Of these, seven (8%) were incidence cancers. Most cancers were radiologically described as solid (n = 52 [61%]). The median tumor size was 18 x 13 mm (range, 6-56 mm). Histopathologic diagnoses revealed 10 (11.6%) bronchoalveolar carcinomas, 55 (64%) adenocarcinomas, 11 (12.8%) squamous-cell carcinomas, two (2.3%) large-cell carcinomas, three (3.5%) carcinoids, and five (5.8%) small-cell lung cancers. Of the 41 cases with follow-up computed tomographic scans, 36 nodules had increased in size. The mean doubling time for all cancers was 259 days (median, 154 days). In women (n = 25), the mean doubling time was 313 days (median, 156 days), while in men (n = 11), the mean doubling time was 137 days (median, 92 days). Overall, 55 lung cancers (68%) were stage I. Most cancers (n = 62 [73%]) were surgically resected. Conclusions: In this cohort, screening detected lung cancer in early treatable stages, and women had more slow-growing adenocarcinomas than men. Most screen-detected lung cancers were surgically resectable.