Much of the rise in lung cancer diagnoses in never-smokers may be explained by historical and current exposure to asbestos, Australian researchers argue.
Although precise causal relationships remain obscure, available data underscore the need to establish appropriate preventative measures and improve screening for lung cancers resulting from asbestos as well as ‘particulate’ (PM2.5) and silica air pollution, they say.
It comes amid declining smoking rates and epidemiological studies suggesting up to 25% of lung cancers may not be attributable to tobacco smoking, as well as rises in the relative proportion of lung adenocarcinomas.
Beyond that, the incidence of asbestos-related lung cancer is estimated at up to six times larger than that of mesothelioma, according to a paper in Lung Cancer (link here).
Led by University of Sydney Professor Emeritus Nico van Zandwijk, the authors make the case that these data point to an “underappreciated oncological issue”, warranting renewed academic focus.
“While the association between fibre dimensions and carcinogenicity of asbestos fibres was a dominant subject of occupational research 40–50 years ago, more recent studies into the epidemiology and molecular pathology of lung cancer associated with environmental (air) pollution have uncovered novel pathways of lung carcinogenesis where small particles play a dominant role,” they write.
“Moreover, the worldwide epidemic of lung cancer in never smokers, that only recently has attracted sufficient attention, has also put air pollution in a prominent causal position.”
In particular, research effort is needed to estimate the proportion of small asbestos fibres potentially contributing to PM2.5 or ‘fine-dust’ air pollution, while better occupational and residential data is required to allow better attribution of lung cancer diagnoses to asbestos, they say.
“As we are living in an increasingly polluted world, this has become an important aim,” note the authors.
They add: “Considering that there were up to five thousand products in the marketplace that contained asbestos in the past, it is virtually impossible to document all exposures. Talcum powders, often containing asbestos, provides an excellent example.”
“The publicity around recent court cases alerted doctors and the public, who had never suspected talcum powder to contain asbestos… job titles are insufficient to exclude historical asbestos exposure.”
The team concluded by stressing that increasing insight into the mechanisms of fine dust-induced pulmonary pathology provided a very strong argument to stop excluding smaller-sized asbestos fibres from having a causative role in lung cancer.
“Considering the increasing proportion of the lung cancer in never smokers epidemic and the scarcity of data on occupational and environmental exposures it is fair to state that asbestos related lung cancer may well be an underappreciated oncological issue.