Biomarkers and Gastric Cancer

Learn why biomarkers are important in your treatment planning

What are cancer biomarkers?

Biomarkers are characteristics that can be measured to provide insights into biological processes. In gastric cancer, biomarkers can reveal details about an individual patient’s cancer. Cancer biomarkers include genes, proteins or specific substances produced by the tumor.

Why are biomarkers important in cancer treatment?

In the early days of cancer treatment, everyone with a specific type of cancer received similar regimens of drugs and/or surgery. Over time, research revealed that tumors, even within the same cancer type, can vary from patient to patient. Cancer biomarkers help oncologists characterize each patient’s tumor and to predict which treatment is most likely to be effective against their individual cancer. Studies indicate that tailoring treatment based on biomarker testing can lead to better outcomes for patients.

The results of biomarker testing are key to precision oncology. By analyzing a patient’s unique biomarker profile, healthcare providers can tailor therapies, such as immunotherapy or targeted therapies, for more effective and less toxic outcomes.

Talk to your doctor about biomarker testing.

Testing for biomarkers

Should every gastric cancer patient receive biomarker testing?

It is important to talk to your oncologist about whether biomarker testing is appropriate for you based on your diagnosis.

What does biomarker testing involve?

Testing can include genomic testing to examine genetic sequences, DNA or RNA tests to look for gene fusions or tests to measure protein levels. Depending on the type of biomarker being tested, tumor tissue may be removed during biopsy or surgery. The samples are sent out to a laboratory for testing.

What are important questions that I should ask my doctor about biomarker testing?

  • When in my treatment plan should I receive biomarker testing?
  • Will you go over the results with me once they become available?
  • Will I need to be tested more than once?
  • If I am not eligible for biomarker testing, can you tell me why?

Will biomarker testing be covered by my insurance plan?

Many insurance plans do cover biomarker testing, especially when it is part of the diagnostic or treatment process. For example, Medicare will cover the cost for genetic testing and biomarker testing for people who meet certain criteria. It is essential to discuss coverage with your oncologist and insurance provider.

Biomarkers can help your doctor tailor treatment to your individual cancer characteristics.

Biomarker Types in Gastric Cancer

There are four common types of biomarkers: diagnostic, prognostic, predictive and monitoring biomarkers.


Diagnostic biomarkers aid in early detection, allowing for timely intervention and improved outcomes by identifying the disease in its early stages.


Prognostic biomarkers offer insights into the likely course of the disease, helping healthcare professionals tailor treatment plans to the patient’s future needs.


Predictive biomarkers inform clinicians about the likely response to specific treatments, facilitating personalized and targeted therapeutic approaches.


Monitoring biomarkers are used to detect signs of disease progression or recurrence and may catch changes before they are visible through traditional monitoring such as imaging scans.

There are a variety of processes that can contain these molecular indicators, including a patient’s genetics, metabolism and breakdown of proteins.


The biomarkers that are currently being used to guide treatment strategies for gastric cancer patients include:


Programmed Death-Ligand 1 is an immune “checkpoint” protein used by some tumors to prevent the immune system from recognizing and attacking cancer cells. PD-L1 expression is a potential indicator of how well a patient might respond to immunotherapy, such as the checkpoint inhibitors pembrolizumab and nivolumab.


HER2 is a protein that promotes tumor growth. In gastric cancer, 7% to 53% of cases exhibit HER2 overexpression or amplification. This biomarker is used to help identify patients who may benefit from HER2-targeted therapies like trastuzumab.


VEGFR2 is a protein that promotes blood vessel formation, providing nutrients to gastric tumors that aid in their survival and growth. Studies show that about 50% of gastric cancer cases exhibit VEGFR2 overexpression. The anti-VEGFR2 antibody ramucirumab is FDA approved to treat advanced gastric cancer.


MSI, or microsatellite instability, is an indicator of how well a patient’s cells are able to correct errors when they undergo processes such as dividing to make new cells. Gastric tumors that are MSI-high may respond well to immunotherapy, making this an important biomarker for oncologists to measure in determining the best course of treatment.

Emerging biomarkers are currently being researched for their potential within gastric cancer treatment. These include:


MET is a gene that produces a protein influencing tumor cell survival and growth. Overactive MET is common in gastric cancer (shown in about 63% of cases). The level of MET protein expression is being studied as a potential biomarker to determine a patient’s eligibility for certain targeted therapies.


FGFR2 is a cell receptor that affects cell survival and growth. Changes in the FGFR2 gene, especially gene amplification, are linked to a poor prognosis in gastric cancer. FGFR2 inhibition is currently being studied in gastric cancer.


CLDN18.2 is a protein expressed on the surface of gastric cancer cells and high expression of it is common in gastric cancer. The antibody zolbetuximab, which kills gastric adenocarcinoma cells by binding to CLDN18.2 on the surface of the cells, is currently under review by the FDA for the treatment of gastric cancer.

Tumor-Infiltrating Lymphocytes (TILs)

The presence of Tumor-Infiltrating Lymphocytes (TILs) in gastric cancer indicates a potential positive response to certain immunotherapies; having more TILs, especially in specific cancer types such as EBV+ and MSI-H, are associated with better responses to certain treatments and longer survival.

Gastric Cancer Foundation is proud to be a Founding Supporter of the national TEST YOUR BIOMARKERS awareness campaign.

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Researchers are focused on identifying and utilizing biomarkers and treatment regimens to target them. In addition to understanding their importance, ongoing biomarker research is concentrating on:

Immunotherapy Response

Scientists are pinpointing biomarkers that can forecast how the immune system will respond to immunotherapy treatment, helping tailor immunotherapy to each patient.

Minimal Residual Disease

This biomarker category is measured by having patients undergo liquid biopsy testing after completing treatment, when no detectable disease remains according to traditional examinations and imaging. By measuring remaining disease at the molecular level through blood tests, this type of testing helps determine whether patients would benefit from more intensive treatment or could potentially avoid aggressive therapy.

Pharmacodynamic Markers

These markers involve biopsies taken before and during treatment to monitor dynamic molecular changes within the tumor. This process helps assess whether the drug is behaving as expected, offering insights into the treatment’s effectiveness.