Endometrial Cancer: Biomarker Testing

This section covers the following topics:

Biomarker tests

Biomarker tests look at samples of blood, tumor or other tissue for changes or abnormalities caused by cancer. Biomarkers can be performed on older tissue or from a new biopsy.  Some tests are ordered routinely while others your doctor may order based on how it might alter their recommendations. These tests can give doctors clues about the cancer, including:

• how fast the cancer is growing
• which treatments are most likely to work
• whether or not the cancer is responding to treatment or growing
• whether or not the cancer has come back after remission

Biomarkers for treatment selection

Biomarker tests may be used to select treatments, and help patients avoid side effects from treatments that will not work for them. Biomarker tests used to select a specific treatment are sometimes called "companion diagnostic tests." These tests may be done on tumor tissue or (in many cases) on blood. See our Biomarker Testing section for more information.

MSI and MMR testing

Experts recommend testing all endometrial cancers for biomarkers known as “microsatellite instability" and, or "mismatch repair deficiency" (dMMR or MMR-D). These biomarkers measure how well the tumor can repair certain types of DNA damage. The results have similar meaning. 

• Microsatellite instablity results are reported as MSI-H (microsatellite instability high), MSI-L (microsatellite instability low) or MSS (microsatellite stable). 
• Mismatch repair results are reported as dMMR or MMR-D (mismatch repair deficient) or pMMR or MMR-P (mismatch repair proficient).
• MSI-high and dMMR cancers are common in people with a Lynch syndrome gene mutation.
• People with advanced or metastatic MSI-high endometrial cancer may respond well to a type of immunotherapy known as an immune checkpoint inhibitor. 
• People with advanced, recurrent endometrial cancer that is not MSI-H, may benefit from the addition of chemotherapy with immunotherapy or a combination of the targeted therapy, Lenvima (lenvatinib) and the immunotherapy agent Keytruda.

Other biomarkers for endometrial cancer treatment

Examples of additional biomarker tests used in endometrial cancer include:

• A rare type of endometrial cancer—known as a uterine sarcoma—may have a genetic change called an NTRK fusion, which can be found on tumor testing. Endometrial cancer with an NTRK fusion may benefit from the targeted therapy Vitrakvi (larotrectinib).
• Estrogen receptor testing is used for prognosis in early stage cancer, and for treatment selection in advanced and recurrent endometrial cancers. 
• HER2 testing is used to find advanced or recurrent endometrial cancers that may respond to drugs that target the HER2 protein.
• Additional tumor biomarker testing, such as POLE and p53 may help identify people who are eligible for certain clinical trials. 

Genetic testing for inherited mutations for treatment selection

About 10 percent of endometrial cancers are caused by an inherited mutation. Some genetic test results can help guide treatment decisions. 

• People with Lynch syndrome are more likely to have MSI-H or dMMR cancers, which are more likely to respond to immunotherapies.
• People with advanced cancer and certain inherited mutations may qualify for a new targeted therapies such as PARP inhibitors, or other agents being tested in clinical trials.   

Visit this page for more information on who should consider genetic testing and the genes associated with hereditary endometrial cancer. 

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