Sensitive genetic testing is increasingly leading to the development and management of gastrointestinal cancer diagnosis and management

John Lindsay Marshall, MD, discusses past, current, and future advances in molecular testing, as well as the unique offerings of tissue and blood testing and the ways these precise methods will ultimately make cancer diagnosis and treatment more efficient and effective.

The field of precision medicine in gastrointestinal (GI) cancer is growing rapidly, leading to a future in which individual patient care is the norm, according to John Lindsey Marshall, MD.

“I look forward to the further development of precision medicine,” Marshall said in an interview. OncLive®.

In the interview, Marshall outlined key points from his presentation on the development of precision medicine in gastrointestinal cancer during fourth annual precision medicine symposium®. Discuss past, current, and future advances in molecular testing, as well as the unique offerings of tissue and blood testing and the ways in which these precise methods will ultimately make cancer diagnosis and treatment more efficient and effective in the future.

Marshall is chief of hematology and oncology, professor of medicine and oncology, and director of the Otto G. Roche Center for Digestive Cancer at Georgetown University’s Lombardy Comprehensive Cancer Center in Washington, DC.

OncLive®What has the evolution of precision medicine looked like in gastrointestinal cancer?

Marshall: We take precision medicine for granted today, but it wasn’t always that way. We started early on by doing a genetic test here, a protein test there. as such [our capabilities] Evolving over the past five to ten years, we’ve realized we need more than one test.

After that, we began to get acquainted with [mutations] that only appeared in large tests, such as next-generation sequencing, whole genome sequencing, or whole transcription sequencing. The future seems more complicated, [as we learn to do] Protein and phosphorous sequencing.

We’ve gone from getting a single snapshot to terabytes of data for a specific patient. Perhaps this development is making us confused now. However, as we go forward, it will make our jobs a lot easier.

What testing options are currently available?

Currently, the current standard of care for nearly every patient with metastatic disease is broad molecular profiling. There are blood tests and tissue tests, and we have to understand what those different tests tell us and what they don’t.

We know something about the checks we will be ordering, [whether they] We need the variance, and what we will see or lose with the test. With genetic testing, molecular profiling, and precision medicine, we haven’t been that smart yet. [The tests differ from each other in] What do they tell you what are you [can find with them]And what you can not find with them, depending on their technology. As technologies evolve, we need to keep up with that, too.

[There are] The main tests that must be performed in all gastrointestinal cancers, and there are specific medical tests that you cannot begin to treat the patient without knowing [the results of]. Not only can you tell what’s under the microscope; You need to know what is in the genes and proteins to test and treat patients.

What are the optimal scenarios for using these key tests?

Our simplest test is immunohistochemistry, the tissue on the slide is stained and, after 48 hours, you know if [the mutation is] Present. HER2 and PD-L1 are [detected through] immunoglobulins.

The next level is genetic testing. Could you [look at] isolated genes, such as BRAF, and see if there is a mutation. Most pathology departments have the technology for this. But as [we now] You want to know all the genes out there, you need a larger piece of tissue, and you need a lab that can do high-throughput sequencing for the next generation.

The evolution then will be the proteomic sequence, as you will need a large enough piece of tissue, and the quality of the tissue will be important, such as whether it is ischemia. We’ll need to understand that, too.

Regarding the blood test, there are two types of tests. One is not tissue-enriched, which means you’re just looking in the blood, not knowing what you’ll find, but looking for common cancer genes that might be mutating in the blood. These are incredibly effective, but some patients don’t void [mutations] In the blood, and therefore you find nothing. They are not hackers, as we call them, or the copy number is not high enough to detect [the mutations] In a simple blood test.

other [type of blood test] It is the fertilized tissue. There, you take a patient’s tumor and sequence it so you know what to look for, and you can dig deeper. These are the types of tests that are used for minimal residual disease [MRD]. [There’s been] Evolution of blood tests. Both are incredibly valuable blood tests, but they have different places in the clinical scenario.

A liquid biopsy is easier than a tissue biopsy; If you have to insert a needle into a patient, it will only be a blood sample [ideal]. This is where all this science is headed, as we will be able to answer most of our questions with a simple blood test.

[However, with blood testing, we miss many mutations, and these tests don’t tell us everything.] The standard today is still a tissue-based test. But if you can’t get a biopsy sample, if the tissue can’t be analyzed quickly enough, or if you know the specific genes to look for, liquid biopsies looking for cancer genes can be effective.

other [benefit of blood testing] is to look at the MRD to see if there is cancer. [In this case,] We don’t care much about the genes involved, [we just want to know]: Is cancer still present? This is another type of liquid biopsy that is looking for a different answer.

What does the future look like in precision medicine?

Precision medicine will not go away. It will be an increasing part of what we do day by day. [In the future,] We may run fewer scans, more blood tests and more precision medicine. General treatments will be less and less; [instead,] There will be specific treatments for individual patients. We won’t have one-size-fits-all treatments so much anymore like [landscape] The division is increasing.

[These advances are] It will make us smarter. We will be more efficient, and [diagnosis and treatment are] In the end it will be easier. We just need to wait the next few years to allow AI and genetic testing technology to come together to make a better world.

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