Low dose CT scan screening versus empiric surveillance in asbestos exposed subjects: Update of ATOM 002 study

Abstract

Background: Low dose CT scan screening (LDCT) has been proven effective in detecting early stage lung cancer in asbestos exposed workers, but there is no evidence based indication concerning the follow up of these subjects. Aim of this study is to evaluate whether LDCT screening, compared with empiric health surveillance program, could be effective in reducing mortality for lung cancer and/or malignant pleural mesothelioma in asbestos-exposed former workers. Methods: The ATOM002 prospective non randomized study enrolled a cohort of 2433 occupationally asbestos-exposed men. The prognostic role of LDCT was investigated through Cox regression in terms of survival for all causes, all cancers, lung cancer and pleural mesothelioma. Multivariate models were adjusted for smoking habits, age at start of follow-up, level of exposure to asbestos and Charlson-Quan comorbidity index. External comparison was possible by estimating the standardized mortality rate ratio (SMR) using Friuli Venezia Giulia regional standard rates (SMR-FVG) and Italian standard rates (SMR-ITA). Results: Among the total population, 926 men were allocated the to LDCT cohort (ATOM002-P) and 1507 to standard follow-up (ATOM002-NP). Lung cancer crude mortality was 99.4 per 100,000 person-year in ATOM002-P (Obs = 8) compared to 430.4 per 100,000 person-year in ATOM002-NP (Obs = 50). Multivariate analysis highlighted a significant mortality reduction in the ATOM002-P cohort (HR = 0.41 IC95% 0.17-0.96). Even though it was observed a reduction of the all-causes mortality (HR = 0.61 IC95% 0.44-0.84), all cancers mortality and pleural mesothelioma mortality were not significantly affected (HR = 0.97 IC95% 0.62-1.50; HR = 0.86 IC95% 0.31-2.41, respectively). Notably, a reduction in mortality of the ATOM002-P cohort was also observed in respect to the general population (SMR-FVG = 0.55 IC95% 0.24-1.09, SMR-ITA = 0.51 IC95% 0.22-1.01). Conclusions: In our study we found a reduction in the risk of death from lung cancer, compared with national figures but no reduction in risk of death from pleural mesothelioma. These data could reasonably be considered within public surveillance programs for selected, high risk, population.