Asbestos Surveillance Program Aachen (ASPA): Cancer mortality among asbestos exposed power industry workers

Background

The time between initial asbestos exposure and asbestos-related disease can span several decades. The Asbestos Surveillance Program aims to detect early asbestos-related diseases in a cohort of 8,565 power industry workers formerly exposed to asbestos.

Research question

How does asbestos exposure patterns affect cancer mortality and the duration of latency until death?

Methods

A mortality follow-up was conducted with available vital status for 8,476 participants (99 %) and available death certificates for 89.9 % of deceased participants. Standardised mortality ratios (SMR) were calculated for asbestos-related cancers. The SMR of mesothelioma and lung cancer were stratified by exposure duration, cumulative asbestos exposure and smoking. The effect of age at first exposure, cumulative asbestos exposure and smoking on the duration of latency until death was examined using multiple linear regression analysis.

Results

The mortality risk of mesothelioma (n = 104) increased with cumulative asbestos exposure but not with exposure duration; the highest mortality (SMR: 23.20; 95 % CI: 17.62–29.99) was observed in participants who performed activities with short extremely high exposures (steam turbine revisions). Lung cancer mortality (n = 215) was not increased (SMR: 1.03; 95 % CI: 0.89–1.17). Median latency until death was 46 (15–63) years for mesothelioma and 44 (15–70) years for lung cancer and deaths occurred between age 64 and 82 years. Latency until death was not influenced by age at first exposure, cumulative exposure, or smoking.

Conclusion

Cumulative dose seems to be more appropriate than exposure duration for estimating the risk of mesothelioma death. Additionally, exposure with high cumulative doses in short time should be considered. Since only lung cancer mortality, not incidence, was recorded in this study, lung cancer risk associated with asbestos exposure could not be assessed and the lung cancer mortality was lower than expected probably due to screening effects and improved treatments. The critical time window of death from asbestos-related cancer is between the seventh and ninth decade of life. Future studies should further explore the concept of latency, especially since large ranges are reported throughout the literature.