The adenocarcinoma-specific stage shift: Closely-repeated low-dose helical CT screening in a high-risk cohort for 10 years

Abstract

1006 Background: Trials of CT screening for lung cancer have not yet proven the presence of a stage shift, to say nothing of a mortality benefit. On the basis of an update from Anti-Lung Cancer Association project, we investigated whether the stage shift did occur during the long-term closely-repeated low-dose helical CT screening in a high-risk cohort. Methods: A total of2,120 participants (mean age 63 yrs, 87% male, and 83% smoker) underwent low-dose helical CT screening semiannually from 1993 to 2004 (median, 3.5 years). Results: Nineteen prevalence and 57 incidence lung cancers were detected. In comparison between baseline and repeated screening, the detection rate was 0.90% vs. 0.32% (P < 0.001) and the tumor size was 24mm vs. 17mm (P = 0.018). Adenocarcinoma (74% and 63%) and stage IA (58% and 79%) were observed most commonly in both screen-groups, respectively, but their proportions showed no significant difference between groups, respectively. Regarding the survival of lung cancer patients, screening type was not a significant prognostic factor. In repeated screening,the detection rate oflung cancer except bronchioloalveolar carcinoma increased significantly depending on CT repeating times (r = 0.50, P = 0.020). Moreover, the proportion of stage II-IV and the tumor size decreased significantly only in invasive adenocarcinoma (r = -0.77, P = 0.007 and r = -0.60, P = 0.029, respectively). Conclusions: The adenocarcinoma-specific stage shift did occur in a high-risk cohort. Considering larger proportion of adenocarcinoma in this population, smokers might benefit from the long-term closely-repeated low-dose helical CT screening. No significant financial relationships to disclose.