In asbestos-related litigation involving cases of lung cancer, the question of whether asbestos was a cause in the development of the plaintiff’s lung cancer is nearly always hotly contested. Cancers are caused by mutations that may be inherited, induced by environmental factors, or result from accidental DNA replication errors. In the context of asbestos exposure allegations, the ensuing battle of the experts is often confined within the category of environmental factors. These can include whether a history of tobacco use is involved as a causative agent, and it can even come down to differences in asbestos fiber types in the case of the debate regarding amphibole versus chrysotile toxicity.
In those cases involving histories of asbestos exposure and tobacco use, defendants will argue that smoking is the leading cause of lung cancer by far, particularly in the absence of an asbestosis diagnosis. Meanwhile, plaintiffs will argue that their smoking history multiplied the effect of asbestos exposure and played a synergistic effect in the development of their lung cancer. Then there are the one-in-five lung cancer patients with no appreciable smoking history. In non-smoking lung cancer cases, asbestos may seem an obvious culprit when looking to environmental risk factors. In recent years, however, medical literature has emerged showing that a substantial number of cancers, including lung cancers, are caused by accidental genetic replication error.
Because of the success of targeted genetic therapies, particularly with non-small cell lung cancer, identifying specific genetic mutations can be key to improving patient outcomes in the fight against certain cancers. As a result, most physicians around the world now order testing for mutation to the epidermal growth factor receptor (EGFR mutation) before initiating therapy in lung cancer cases.
As this testing has become standard, the emerging data is leading to a body of evidence demonstrating that the EGFR mutation occurs spontaneously – that is, not the result of any environmental or hereditary factors. This is a significant development in asbestos-related litigation. For individuals who test positive for the EGFR mutation, the implication is that no matter one’s exposure history to asbestos, to tobacco products, to radon, etc., the growing body of literature is showing that the mutation itself is the cause of the plaintiff’s cancer.
This is creating a new battlefield for the litigants’ experts as plaintiffs will use decades of epidemiological study regarding asbestos and cancer to cast doubt on the notion of “accidental” cancer. Plaintiffs will argue that the EGFR mutation is not the initiator of the cancer and/or the mutation is caused by environmental factors like asbestos exposure.
However, there is no evidence at present that asbestos exposure is a cause of EGFR mutation. In patients who have a history of asbestos-exposure, EGFR mutations are observed at a significantly lower rate and EGFR mutations are also more commonly observed in patients with light or no smoking history. This suggests that at least these two environmental factors are not playing a causative role in development of an EGFR mutation.
Hereditary factors also do not appear to be at play. The EGFR mutation is somatic—it affects a cell and is then passed down to all the progeny of the mutated cell. This should be contrasted with a hereditary germline mutation that is passed from one’s parents. Unless and until further study reveals an environmental factor, the EGFR mutation appears to fall into the category of accidental mutation that leads to cancer.
The consequences in asbestos litigation are clear. Defense counsel should be reviewing plaintiffs’ medical records for EGFR testing in lung cancer cases. This testing should be present in the treating records in cases involving non-small cell lung cancer, especially adenocarcinomas. Where a plaintiff’s tumor exhibits EGFR mutation positivity, Defense counsel need to then assess their expert requirements commensurate with their liability exposure and retain experts accordingly for this emerging battlefield for the experts.
CMBG3 Law LLC has represented clients in toxic torts matters, especially with respect to asbestos, for many years. We provide the most current legal advice to our clients by staying on top of developments in science, medicine, and regulations regarding a wide variety of substances and products used by consumers every day. If you have any questions or would like more information about the genetic defenses referenced in this article, please contact Gilliam Stewart, Esq. (email him or 415-957-2322).