A 20-year Follow-up of the International Early Lung Cancer Action Program (I-ELCAP).

Background The low-dose CT (≤3 mGy) screening report of 1000 Early Lung Cancer Action Program (ELCAP) participants in 1999 led to the International ELCAP (I-ELCAP) collaboration, which enrolled 31 567 participants in annual low-dose CT screening between 1992 and 2005. In 2006, I-ELCAP investigators reported the 10-year lung cancer-specific survival of 80% for 484 participants diagnosed with a first primary lung cancer through annual screening, with a high frequency of clinical stage I lung cancer (85%). Purpose To update the cure rate by determining the 20-year lung cancer-specific survival of participants diagnosed with first primary lung cancer through annual low-dose CT screening in the expanded I-ELCAP cohort. Materials and Methods For participants enrolled in the HIPAA-compliant prospective I-ELCAP cohort between 1992 and 2022 and observed until December 30, 2022, Kaplan-Meier survival analysis was used to determine the 10- and 20-year lung cancer-specific survival of participants diagnosed with first primary lung cancer through annual low-dose CT screening. Eligible participants were aged at least 40 years and had current or former cigarette use or had never smoked but had been exposed to secondhand tobacco smoke. Results Among 89 404 I-ELCAP participants, 1257 (1.4%) were diagnosed with a first primary lung cancer (684 male, 573 female; median age, 66 years; IQR, 61-72), with a median smoking history of 43.0 pack-years (IQR, 29.0-60.0). Median follow-up duration was 105 months (IQR, 41-182). The frequency of clinical stage I at pretreatment CT was 81% (1017 of 1257). The 10-year lung cancer-specific survival of 1257 participants was 81% (95% CI: 79, 84) and the 20-year lung cancer-specific survival was 81% (95% CI: 78, 83), and it was 95% (95% CI: 91, 98) for 181 participants with pathologic T1aN0M0 lung cancer. Conclusion The 10-year lung cancer-specific survival of 80% reported in 2006 for I-ELCAP participants enrolled in annual low-dose CT screening and diagnosed with a first primary lung cancer has persisted, as shown by the updated 20-year lung cancer-specific survival for the expanded I-ELCAP cohort. © RSNA, 2023 See also the editorials by Grenier and by Sequist and Olazagasti in this issue.

CT- and computer-based features of small hamartomas.

PURPOSE: To identify characteristic computed tomographic (CT) and computer-derived features of hamartomas manifesting as small pulmonary nodules. METHODS: Individuals with a diagnosis of hamartoma were identified among participants in the International Early Lung Cancer Action Program and were included if there thin section CT images that included the entire nodule. The CT findings were reviewed to determine the nodule consistency (solid, part-solid, nonsolid), nodule diameter (average of length and width), shape (round, lobulated, neither) and edge (smooth, not smooth). Computer measures of nodule compactness, sphericity, surface regularity and gradient (change in gray-scale between the nodule and the surrounding parenchyma) were determined. Volume doubling time (VDT) was also determined for those with at least two scans with similar imaging acquisitions. RESULTS: A total of 21 cases of hamartomas that had histologic or cytologic confirmation were identified. The median age was 60 and 12 (57%) were men. Average diameter was 10.7 mm (5-20.7 mm). All were solid in consistency and were described by the radiologist as having either round or lobulated shape with a smooth edge. None had pathognomonic radiologic findings for hamartoma. Computer measures demonstrated that all were compact and spherical, with a regular surface and a sharp margin between the nodule and surrounding parenchyma. Of nine on whom the VDT could be calculated, eight had VDTs longer than 450 days. CONCLUSION: Both radiologist and computer derived features of small hamartomas suggest a consistent presentation for these lesions which may be helpful in distinguishing them from other types of nodules.