Panel Testing Part 1: The genetics arm race leads to clinical questions

May 14, 2015


By: David Shifrin, PhD
Science Writer, Filament Life Science Communications

Bundling. It’s done in practically every industry, from adding optional features on a new car, to internet and phone service, to academic journal subscriptions. Medicine is no exception. These days, bundling is common in the world of genetic testing. The use of panel tests has increased significantly over the past several years, accounting for an ever-increasing proportion of all genetic tests performed.

One of the significant drivers of panel testing was not medical in nature, but rather an issue of business and intellectual property. The genetics community has expressed concern about this development, which came about in 2013 with the US Supreme Court’s ruling in the well-known Myriad case. With Myriad’s BRCA patent invalidated, competitors jumped in to claim their slice of the breast cancer testing market. In order to differentiate and putatively add value, these newcomers started offering tests with multiple genes. More data, more concerns over what to do with it all. It’s a story that we end up telling in almost every blog post here.

(It is worth noting that Myriad still has an edge in the BRCA testing market. Seeking Alpha recently pointed out that “the company’s proprietary database of 16,000 gene mutations for BRCA testing is a unique dataset which will allow it to provide more accurate results” and therefore remain a leader in the field. Though this is speculation, it seems quite possible that the race to more extensive and complex panels will only increase, as Myriad seeks to find new ways to maintain its position.)

With less than two years having passed since the Myriad decision, the debate about when panel testing is appropriate continues. Last year, a paper in the Journal of Genetic Counseling encapsulated the issue with the statement that, “Since technological advances seem to be outpacing the clinical considerations of panel testing, it is important to address these issues and identify gaps in our knowledge as the demand for such tests continues to grow.”

The ASCO Post published an article on April 10, 2015 titled “Should Oncologists Be Ordering Breast Cancer Gene Panels?” The post covers a recent conference debate between two oncologic surgeons. Importantly, the surgeon opposed to routine testing pointed out that panel tests for breast cancer don’t meet several WHO standards regarding the level of risk and the actionability. “’For most genes in the panel, we have limited data on cancer risk and penetrance and no consensus on the management if mutations are found,’ [Dr. J. Michael Dixon] said.”

On the other side of the discussion, Dr. Pat Whitworth suggested that panel tests should become routine parts of the clinical workflow. For one thing “We’ve come too far, the tests are available, and we need to use them properly on behalf of our patients.” Even if some mutations are of unknown significance, panel testing is valuable because it can help prevent what the article calls the “’diagnostic odyssey’ that prevails when BRCA1/2 results are negative.” Whitworth also suggested that concerns about emotional distress caused by the finding of mutations and/or the presence of mutations of unclear significance are overstated. Individuals today are more aware of the breadth of possible mutations (in principle if not specifically), and they generally want to know about them. Moreover, “Dr. Whitworth believes that [variants of unknown significance] will be sorted out once broader testing is achieved and with the aid of [research] and education of physicians.”

The session described in the ASCO Post article therefore serves as an excellent encapsulation of the issue surrounding panel testing. Whitworth may be right in saying that, overall, the aggregated population would prefer to have more information about their genetic predispositions, regardless of actionability. On the other hand, examples of the opposite are easy to find. Individuals may prospectively prefer not to have the added stress of potential non-actionable results or retroactively wish they had not learned about them. This point will be covered in more detail in the next post.

May 14, 2015


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