Pulmonary nodules detected by thoracic computed tomography scan after exposure to asbestos: diagnostic significance

To analyse the relationship between pulmonary nodules detected by radiologists using computed tomography and cumulative exposure to asbestos or asbestos-related pleuro-pulmonary diseases in 5662 asbestos-exposed subjects, and the relationship between pulmonary nodules and thoracic cancer, to determine whether a specific surveillance strategy based on cumulative asbestos exposure should be adopted.

Standardised incidence and mortality ratios (SIR) for lung cancer and pleural mesothelioma were calculated in patients with and without mention of pulmonary nodules and compared using comparative morbidity figures.

A significant excess incidence of primary lung cancer and pleural mesothelioma was observed among subjects presenting with pulmonary nodule(s) (SIR respectively 1.95, 95%CI 1.22-2.95, and 11.88, 95%CI 3.20-30.41). However, there was no significant relationship between pulmonary nodules mentioned by radiologists and cumulative asbestos exposure or between pulmonary nodules and the presence of asbestos-related benign diseases.

This study confirms the expected excess prevalence of lung cancer in subjects presenting with pulmonary nodules according to the radiologist's report, and shows the absence of relationship between the presence of nodules and level of cumulative asbestos exposure. Our study therefore offers no argument in favour of specific surveillance modalities based on estimated cumulative asbestos exposure.