If you’ve been diagnosed with endometrial cancer, your doctor may recommend biomarker testing to help guide your treatment plan. This testing can identify specific molecules, genes, or proteins in your tumor cells that aren’t present in healthy uterine tissue. These molecule markers, or biomarkers, can provide essential information that can benefit you on your cancer treatment journey.

How Does Biomarker Testing Work?

Biomarker testing — also called tumor subtyping, genomic profiling, or molecular testing — analyzes your cancer cells to identify specific traits that can guide treatment decisions. This testing can be done on tissue samples taken from a biopsy or surgery, or through blood tests that detect markers released by cancer cells. Your doctor sends these samples to a lab, where they are tested to see whether biomarkers are present. Laboratories use a variety of tests, such as gene sequencing or immunohistochemistry, to look for genetic mutations or abnormal proteins.

While biomarker tests can look for several types of markers — including genetic mutations and protein expression levels — the most common testing for endometrial cancer looks at markers called mismatch repair deficiency (MMR-D) and microsatellite instability.

Benefits of Biomarker Testing

Recent advancements in biomarker testing have improved our understanding of how these tests can benefit people with endometrial cancer. In this article, we’ll explore the key advantages of biomarker testing and how it can help improve your endometrial cancer treatment outcomes.

1. Finding Effective Treatments

One of the most important benefits of biomarker testing is that it can help doctors find the treatments that are most likely to work for your specific type of cancer. For example, some drugs can target changes resulting from a biomarker that is only found in cancer cells and kill the cancer cells, while leaving the healthy cells unharmed.

Doctors use different systems to look for biomarkers and assign your cancer a risk subgroup. If you have high-risk cancer, you may need more aggressive therapy. These systems, such as the Cancer Genome Atlas (TCGA) Molecular Classification of Endometrial Cancer and the Proactive Molecular Risk Classifier for Endometrial Cancer (Promise), assign risk based on biomarkers, including:

• Mismatch repair deficiency (also called deficient mismatch repair, or dMMR) — This biomarker shows that your cancer cells have abnormalities in certain proteins that are supposed to fix gene mutations, which may cause mutations to build up in your tumor.
• POLE mutations — This means you have multiple mutations in a gene called POLE, which can lead to more mutations in your tumor cells.
• Copy number high — This means there are many amplifications (copies) or deletions of genes throughout your cancer cells.
• Copy number low — This means there are very few gene amplifications and deletions in the genes in your tumor.

Biomarker testing can be especially helpful for people with tumors that do not respond to standard chemotherapy treatments. This may occur if you have advanced-stage endometrial cancer or if your cancer recurs, or returns, after being treated. Biomarker testing can identify immunotherapies or targeted therapies that may work better than toxic chemotherapy medications.

For example, the U.S. Food and Drug Administration (FDA) has approved three immunotherapy drugs as treatments for advanced or recurrent endometrial cancer with dMMR: dostarlimab (Jemperli), pembrolizumab (Keytruda), and durvalumab (Imfinzi). When combined with chemotherapy, both dostarlimab and pembrolizumab have also been approved to treat non-dMMR advanced endometrial cancer.

Biomarker testing can also help your doctor find “off-label” treatment options. This means that while a specific treatment may not be FDA-approved for endometrial cancer, it may still work for you because it targets a certain biomarker in your cancer cells.

2. Assessing How Well Treatments Are Working

Your doctor may recommend biomarker testing at several points in your treatment journey to check whether treatments are successfully killing your cancer cells. For example, if your cancer cells contain a certain biomarker, the levels of this biomarker should drop if your treatment plan is killing the cancer cells.

Tumors also release tiny pieces of DNA into the blood. This is known as circulating tumor DNA (ctDNA). Using different techniques, doctors can test the ctDNA found in the blood for any genetic changes or mutations. This can help track how well your treatment is working and might even detect cancer recurrence earlier.

3. Helping You Avoid Side Effects

When you know which treatments are most likely to work, you can also know which ones are more likely to fail — and stay away from them. Some biomarkers may even make certain treatments ineffective, so this type of testing helps you understand which therapies to avoid.

This is important, because most cancer treatments come with side effects. Research has shown that when you experience a lot of side effects or take multiple medications, you are less likely to stick to your treatment plan. This can make your cancer harder to treat and lead to worse outcomes. By focusing on the treatments that are likely to be effective, you increase your chances of treatment success.

Experiencing treatment-related side effects can also affect your well-being and quality of life. Using biomarker testing to rule out certain treatments can help make your treatment journey easier.

Read more about how to get support as you treat endometrial cancer.

4. Informing Your Prognosis

Most people diagnosed with endometrial cancer have a good prognosis (outlook). However, certain biomarkers serve as prognostic factors — they help doctors understand how serious the disease might be. For example, changes in the tumor protein 53 (TP53) gene may signal a poor prognosis, while mutations in the POLE gene are linked to a lower chance of your cancer coming back.

One study found that multiple biomarkers in the blood were linked to endometrial cancer survival rates. Researchers found that people with this endometrial cancer were likely to have a worse prognosis when they had high levels of the following:

• Cancer antigen 125 (CA-125)
• Cancer antigen 15-3 (CA 15-3)
• C-reactive protein
• D-dimer

Understanding your prognosis helps you make decisions about your cancer treatment plan. For example, if biomarker testing shows that your cancer may grow and spread more quickly, you may want to use more aggressive treatments. Knowing your prognosis also helps you better understand what to expect and make a plan for your future.

5. Qualifying You for Clinical Trials

Clinical trials are research studies that test new treatment plans to see if they are safe and effective. If you join a clinical trial, you may receive new therapies with benefits and side effects that may not yet be fully understood. However, these treatments could be more effective than those currently available through your health care team.

Many clinical trials focus on certain types of cancer, such as advanced endometrial cancer. However, some trials also look for people with certain biomarkers. This may be the case for clinical trials that target a specific type of protein or gene change.

If you’re interested in joining a clinical trial, talk to your doctor to find out which ones might be best for you. You can also visit websites like ClinicalTrials.gov or the National Cancer Institute’s database of clinical trials to learn about ongoing studies.

6. Showing Genetic Changes That May Affect Your Family

Biomarker testing is different from genetic testing. Biomarker testing looks for changes or mutations that developed within your uterine cancer cells that aren’t found in healthy cells. These changes do not run in families.

Genetic testing, however, looks for gene changes in all of your body’s cells. This type of mutation is called a germline or inherited mutation. It can be passed down from parent to child. Having a germline mutation increases your risk of developing cancer. If your family members also have the mutation, their risk may be higher too.

Sometimes, biomarker tests can show changes that are actually inherited mutations. The results of biomarker testing will show whether you may need additional genetic testing, which can help your family understand their levels of cancer risk. Ask your doctor whether genetic testing could be helpful for you and your family.

Talk With Others Who Understand

On MyEndometrialCancerTeam, the site for people with endometrial cancer and their loved ones, members come together to gain a new understanding of endometrial cancer and share their stories with others who understand life with the condition.

Are you living with endometrial cancer? Did you have biomarker testing done on your cancer cells? Share your thoughts and experiences in the comments below or post to your Activities page.