[co-author: Drew McNeill]

Photo by National Cancer Institute on Unsplash

No painful procedure or biopsy needed. We can test our blood to diagnose and even predict cancer.

The Human Genome Project, a joint effort between the U.S. Department of Energy and the National Institutes of Health, began in 1990 and was completed in 2003. The goal of the Project was to map all the genes of the human DNA. Genomic medicine has come a long way since then. In 2020, we can test a cancer patient’s blood (via liquid biopsy) to direct personalized medical decisions about treatment.

Liquid biopsy can also identify individuals with, or at risk for, hereditary cancers. Clinicians routinely use germline (hereditary) DNA genetic testing to inform clinical decisions surrounding cancer treatment and surveillance. For example, identification of a germline pathogenic variant in BRCA1 in a female patient with breast cancer could be the determining factor in her decision to pursue bilateral mastectomy vs lumpectomy or her eligibility for a particular therapy. But DNA testing alone is often inconclusive, with anywhere from 2% to 44% of identified variants classified as variants of uncertain significance (VUS). Now, pairing it with RNA genetic testing has provided a breakthrough, by resolving a substantial proportion of VUS either as benign or pathologic. RNA genetic testing can also identify mutations that DNA-only genetic testing misses.

It’s not just a lab theory. Pairing +RNAinsight™ with hereditary cancer DNA tests, Ambry Genetics has offered a commercially available concurrent RNA and DNA genetic testing for hereditary cancer risk since 2019. In a pilot study, clinicians reported that RNA/DNA testing changed clinical recommendations for 44% of patients and 78% of families, compared to DNA testing results alone. In addition to the technical advantages discussed above, there is a practical advantage of concurrent testing as compared to sequential testing: In sequential testing, 90 percent of patients dropped out after DNA testing without sending in samples for RNA testing.

It’s all fascinating from a scientific perspective, but how does it matter in a lawsuit?

Say you are involved in a medical malpractice case or a product liability case related to cancer. Determining where the cancer originated is often the first step because it helps understand if the defendant’s product or services had something to do with the plaintiff’s cancer and/or outcome. But it is sometimes impossible to tell where a patient’s cancer originated. Advanced imaging techniques (like CT and PET scanning) have been helpful, but the primary (originating) site of some cancers still remain unknown. In some of those difficult cases, liquid biopsies may be able to help solve the mystery.

And there is sometimes a question of what caused the cancer. As discussed above, knowledge of genetic mutations linked to a hereditary likelihood of getting cancer, like a BRCA1 mutation causing breast cancer, is growing. Inherited or not, knowledge linking genetic mutations and mutation patterns to various features of cancer (tissue type, cell type, primary site, etc.) or patient profile (age, sex, race, exposure to certain carcinogens, etc.) is also growing. Genetic testing may even provide evidence of an independent cause of cancer, unrelated to the defendant’s product or service.

Also, genetic testing may reveal a patient’s genetic mutations that could cause other cancers or other significant diseases (autoimmune diseases, dementia, etc.). Even when the defendant’s product or services were related to the plaintiff’s cancer or outcome, genetic mutations that would likely have shortened the plaintiff’s lifespan and/or significantly worsened their future quality of life may impact damages to which that plaintiff may be entitled.

As medical knowledge advances, lawyers must keep pace. The rules of ethics require lawyers to be competent — for litigators, to have the necessary understanding to properly prosecute their clients’ claims, or defend their clients from poorly-founded claims. Understanding the implications of genetic testing would then be not only helpful, but also necessary, for litigators going forward.

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