Genetics Research Raises Questions for Toxic Torts on Cancer

What caused the disease? That is the question in many toxic tort cases.

When defending them, the inquiry has two parts: whether the product can cause the disease in question and whether the plaintiff was exposed to enough of it for it to have done so. With cases involving cancer, particularly mesothelioma, genetic science adds to the analysis and provides information that may change the question entirely in some cases.

My experience with these issues arises from the defense of asbestos cases. However, emerging medical research that has blurred the link between asbestos and mesothelioma may have implications for other toxic torts involving cancer.

Cancer is a genetic disease caused by gene mutations that control how cells grow and multiply. While cells are the body’s building blocks, genes are sections of DNA in cells that control cell growth. Hundreds of DNA/genetic changes have been discovered that help cancer form, grow, and spread.

There are multiple causes of malignant mesothelioma, some of which are unrelated to asbestos.

The epidemiological evidence indicates that most pleural mesotheliomas in women, and almost all peritoneal mesotheliomas in both women and men in the US, appear unrelated to asbestos.

In July 2019, many of the world’s foremost experts detailed state-of-the-art knowledge on the development of mesothelioma. Regarding genetics, the authors stated that “a growing percentage of cancers are attributed to inherited mutations of DNA repair genes and of other genes that, when mutated, accelerate the accumulation of DNA damage and/or the percentage of cells carrying DNA damage”—and that such concepts apply to mesothelioma.

Broadly, there are two types of genetic cases: somatic or random genetic mutations and germline genetic mutations.

Somatic random mutations develop because of DNA changes that occur during stem cell divisions. These mutations arise naturally and accumulate as a person ages. Stem cell division occurs continuously and requires a faithful replication of the highly complex genetic information contained within the genome and cell nucleus. Random mistakes or mutations (replication errors) occur continuously and with increasing frequency over time, with the capacity of the host to efficiently identify and correct such mutations diminishing with age.

Random mutations account for two-thirds of the risk for many types of cancer. In such cases, no exposure to an exogenous agent is required for tumor initiation.

Some mesotheliomas are linked to inherited germline mutations. Pathogenic germline mutations of BAP1 and of other tumor suppressor genes have been detected in approximately 12% of patients. This subgroup of genetically linked mesotheliomas occurs in individuals who rarely report asbestos exposure.

While heritable gene mutations can predispose an individual to cancer—that is, lower the amount of exposure necessary to cause disease—they can also be sufficient to cause cancers, including mesothelioma, in and of themselves. Put another way, the presence of a heritable germline mutation, absent or independent of extrinsic factors such as asbestos exposure, can cause mesothelioma.

Some takeaways are worth considering. First, when examining a toxic tort case involving cancer, it may not always be the “toxin” that is to blame. For practitioners, if the toxin in question may not be to blame, one should consider whether to pursue genetic testing through discovery if there is no agreement. This typically involves obtaining a blood or saliva sample from the plaintiff.

Plaintiffs’ counsel often oppose such testing. When that happens, one must show—either through a documented family history of relevant cancers or indications in pathology findings suggestive of a genetic mutation—that the testing is necessary to determine whether the genetic mutation is present. Expert affidavits are usually needed to persuade a court to allow testing.

Second, genetic germline mutations don’t automatically turn a plaintiff into an “eggshell plaintiff.” The eggshell plaintiff doctrine provides that a person’s weakened condition or susceptibility to injury or disease isn’t a defense against the claim that they were injured or contracted a disease. The fact that less trauma or exposure was necessary to bring about the harm also isn’t a defense.

Here, the plaintiff would argue that the genetic mutation or predisposition only had one effect—lowering the amount of toxin necessary to bring about the disease (for which there is no defense). But given that the mutation itself can cause the disease, the eggshell plaintiff doctrine shouldn’t apply to all cases.

This article does not necessarily reflect the opinion of Bloomberg Industry Group, Inc., the publisher of Bloomberg Law and Bloomberg Tax, or its owners.

Author Information

Anthony J. Sbarra is shareholder at Segal McCambridge in the firm’s Boston office and focuses his practice on product liability and toxic tort cases.

Write for Us: Author Guidelines