Asbestos-related disease is a worldwide problem. Pleural plaques (PP), asbestosis, malignant mesothelioma, pleural effusion, diffuse pleural thickening, and bronchogenic carcinoma constitute asbestos-related diseases with the pleural plaques being the most common manifestation. Detection of early pleural and parenchymal changes on computed tomography (CT) is more sensitive than chest X-ray .
In the present study, we aimed to detect and evaluate the different radiological patterns of asbestos-related lung disease and its complication by including 40 patients with asbestos-related lung disease with mean age of the studied patients being 55.4 years with male predominance at 80%. Of patients, 55% were smokers, 30% were ex-smokers, and 15% were non-smokers.
In the current study, we found that the mean duration of asbestos exposure was 22.73 years and the mean time since first exposure was 23.75 years with a latent duration about 19.36 years.
In a study by Ahn et al. , they found that the mean duration of Asbestos exposure for the compensated workers was 16 years. The most common duration of exposure involved the group exposed to asbestos for 10–20 years (eight cases). The mean duration of the latency period was 22.6 years. The most common duration of the latency period was 20–30 years.
In the present study, we found that 40% of patients showed malignant lesions in the form of mesothelioma in 27.5% and bronchogenic carcinoma in 12.5% of cases. On the other hand, 60% showed non-cancer lesions in the form of pleural effusion in 7.5%, calcified pleural plaques in 40%, lung fibrosis in 7.5%, and rounded atelectasis in 5%. In a study by Çoşğun et al. , it was found that pleural plaques due to environmental asbestos exposure were found in 66 of the 75 patients on chest CT distributed as follows: 64 (96.6%) costal plaques, 44 (66.6%) diaphragmatic plaques, and 9 (13.6%) pericardial plaques.
Comparing patients diagnosed with malignant and benign lesions, there were no significant differences as regards age, sex, smoking status, and presenting symptoms.
As regards smoking status in contrary to our result, the bulk of epidemiologic evidence implicates asbestos as a carcinogen, the effect of which is augmented by cigarette smoking. A synergistic relationship between the two carcinogens is commonly accepted, and a review of 23 studies addressing smoking and asbestos exposure lends support to a multiplicative interaction .
Ιn a retrospective study of 98,912 asbestos workers, Frost et al.  demonstrated that the interaction between smoking and asbestos exposure was greater than the additive (i.e., multiplicative) to the occurrence of lung cancer, while lung cancer risk remained increased even 40 years after smoking cessation.
In the current study, we found that there were significant differences between the two groups as regards duration, time of exposure, and latent period as cancer susceptibility increases in patients with longer duration of exposure and longer latent period, and by univariate analysis, the significant factors affecting malignancy of lesions were duration of exposure and time since first exposure.
This was also detected by other studies as they revealed that the risk of malignant mesothelioma MM is very low in the first 10–15 years . The mean latency period has been repeatedly found to be 30–40 years, and more than 90% of MM were diagnosed more than 15 years after the first asbestos exposure [11, 12].
However, MM cases were reported with a very brief latency period and epidemiologic studies support the hypothesis that heavy asbestos exposure may result in a shorter induction period .
Bianchi et al.  investigated 325 mesothelioma cases that occurred in the shipbuilding industry; 15.7% (50 cases) had latency < 10 years.
The consensus of international experts is that a minimum of 10 years from the first exposure is required to attribute MM to asbestos exposure . This difference may be caused by a short history of occupational asbestos use and relatively younger compensated workers compared to other countries. For example, reviewing the series of 557 MM of the pleura in Italy, latency period ranged from 14 to 75 years (mean, 48.8 years; median, 51.0 years) .
Moreover, Mastrangelo et al.  showed that a significant increase in asbestos risk was found with increasing cumulative asbestos exposure, but not with time since first exposure, peak exposure, duration of exposure, age, and smoking. It can be seen that the significant risk factors were cumulative exposure to asbestos, time since first exposure and peak exposure for pleural plaques, and time since first exposure for diffuse pleural thickening.