How Is Gastric Cancer Biomarker Testing Conducted?
How Is Gastric Cancer Biomarker Testing Conducted? from Patient Empowerment Network on Vimeo.
Biomarker testing is essential for gastric cancer patients, but how is it conducted? Expert Dr. Matthew Strickland explains the methods of biomarker testing and the common biomarkers associated with gastric cancer.
Dr. Matthew Strickland is a medical oncologist at Massachusetts General Hospital. Learn more about Dr. Strickland.
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Transcript:
Katherine Banwell:
So, how is biomarker testing conducted? Is it via a blood test?
Dr. Matthew Strickland:
This is also an excellent question. Biomarkers can often be tested in different ways. Most of the biomarkers that I’ve outlined start by being tested via cell surface expression of those proteins. Basically, that translates to once the biopsy of the tumor is taken out and is now in the pathology lab, a pathologist can apply different stains to identify these proteins and biomarkers.
Then, they can assess, in other words, quantify the level of expression. This method is called immunohistochemistry. I would say it’s a fair statement to think this is a first pass method of detecting biomarkers.
But it’s not the only one. Beyond that…there’s, for example, HER2 can sometimes reflex to assessing the copy number of the gene. So, we’re no longer talking at the protein level. Right now, we’re talking about using a method…the acronym is FISH, which stands for fluorescence in situ hybridization. This is a method to quantify the number of copies of the gene.
If the cancer has indeed overexpressed HER2 to gain a growth advantage, then often we’ll see a very significantly high copy number. Then, to address your question regarding biomarkers detected in the blood, this is also a new area, relatively new. We know that there are fairly effective tools to test for circulating tumor DNA.
Backing up for a moment, cancer cells can – let me rephrase. Cancer cells will to some degree shed their DNA into the bloodstream. We are able to detect that unique DNA to some degree. So, these tools, which are generally called circulating tumor DNA assays, there are different companies. The names of their products can be different. But they’re becoming increasingly effective at detecting tumor DNA in the blood.
So, there are several approvals for these tools. But this can get a little bit tricky. Because the tools are so new, they’re not yet integrated into our standard management. So, perhaps, at larger cancer centers you might see providers utilizing these tools, but it might not be offered at every location.
