Second Study Confirms Pleural Mesothelioma Risk Plateau

Another new study has confirmed the idea that pleural mesothelioma risk does not appear to increase indefinitely after asbestos exposure, but instead may eventually hit a plateau.

The newest study involved more than 1,800 asbestos cement workers in Pavia, Italy. Researchers in the department of public health at the University of Pavia and the University Eastern Piedmont in Novara computed the mortality ratios for the major causes of death among the workers.

Major Causes of Death Among Asbestos Workers

Not surprisingly, they found that asbestos workers faced a higher risk of dying from pleural or peritoneal mesothelioma, lung cancer, and asbestosis, all of which have been directly linked to asbestos exposure.

In contrast to some other mesothelioma studies, the researchers did not find an elevated risk of laryngeal cancer among the asbestos workers. There was an increase in ovarian cancer deaths, however it was deemed not to be statistically significant.

Among the male asbestos cement workers, the risk of contracting pleural mesothelioma appeared to correlate with how long they were exposed to asbestos, but not with how long the disease took to develop (latency period). Mesothelioma has one of the longest latency periods of any cancer, which can last up to 40 years.

The Mesothelioma Risk Ceiling

Although some previous studies have suggested that, the older an asbestos worker gets, the higher his or her chances are of developing malignant mesothelioma, several newer studies – including this one – indicate that this is not the case.

Instead, mesothelioma risk appears to hit a plateau, and may even begin to decrease slightly, at about 40 years since first asbestos exposure.

“Our results do not support the hypothesis that pleural malignant mesothelioma risk indefinitely increases after exposure, suggesting instead that the alternative hypothesis of a risk plateau or decrease after a time since first exposure of more than 40 years is more consistent with the observed data,” states the report in a recent issue of the American Journal of Industrial Medicine.

Confirming Earlier Data

An even larger Italian study published earlier this month reached a similar conclusion.

That study used data from 43 previously-studied groups for a total of more than 51,000 people, primarily asbestos cement and shipbuilding workers.

Those figures, published in Occupational and Environmental Medicine, indicated that the rate of pleural mesothelioma among the studied workers tended to increase during the first 40 years after initial exposure but then plateaued.

Notably, the suggestion of a mesothelioma risk plateau in both studies applies to the pleural variety of mesothelioma around the lungs but not necessarily to the peritoneal variety, which grows on the membrane that lines the abdomen.

Sources:

Oddone, E, et al, “Mortality in asbestos cement workers in Pavia, Italy: A Cohort study”, August 18, 2017, American Journal of Industrial Medicine, Epub ahead of print

Farrante, D, et al, “Italian pool of asbestos workers cohorts: mortality trends of asbestos-related neoplasms after long time since first exposure”, August 3, 2017, Occupational and Environmental Medicine, Epub ahead of print