Genetic testing and biomarker testing for fallopian tube, ovarian and primary peritoneal cancer

This section covers the following topics:

• Genetic testing for inherited mutations for treatment selection
• Tumor biomarker testing for treatment selection

Genetic tests for inherited mutations for treatment selection

All people diagnosed with ovarian cancer should be offered genetic testing for an inherited mutation. Genetic test results  may be used to guide treatment selection for people diagnosed with ovarian cancer.  

• People with advanced ovarian cancer who test positive for an inherited BRCA1 or BRCA2 mutation may benefit from treatment with a type of targeted therapy known as a PARP inhibitor.
• People who test positive for other inherited gene mutations may qualify for clinical trials looking at targeted therapies to treat hereditary ovarian cancer. 
• People who test positive for a Lynch syndrome gene mutation may benefit from treatment with an immunotherapy agent. 

Biomarker testing 

Biomarker tests look at samples of blood, tumor or other tissue for changes or abnormalities caused by cancer. 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

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. 

Biomarkers for treatment selection

Examples of biomarker tests used in fallopian tube, ovarian and primary peritoneal cancer include:

• Tests can be done to look for BRCA1 or BRCA2 gene mutations in the tumor. Women who test positive for a BRCA1 or BRCA2 mutation in their tumor may benefit from a type of therapy known as a PARP inhibitor. A tumor test positive for a BRCA1 or BRCA2 mutation in one of two situations:, 
  • when women who have an inherited mutation in BRCA1 or BRCA2 develop ovarian cancer, their tumor is very likely to display the same mutation.
  • women who test negative for an inherited mutation in BRCA1 or BRCA2 may still develop an acquired BRCA mutation in their tumor. Women with a BRCA mutation in their tumor may also respond well to PARP inhibitor treatment.  
• A tumor test for a marker called HRD (homologous recombination deficiency) can help women with advanced ovarian cancer learn if they may benefit from maintenance therapy with a PARP inhibitor.  
• Some ovarian cancers will have an abnormality known as MSI-high (“microsatellite instability high") also known as "mismatch repair deficiency" (dMMR or MMR-D). MSI-high cancers are common in people with a Lynch syndrome gene mutation. These cancers may respond well to a type of treatment known as an immune checkpoint inhibitor. One example of an immunotherapy agent used for MSI-H cancers is Keytruda (pembrolizumab).

Biomarkers to monitor recurrence or response to treatment

CA125 is a type of protein that is produced in large amounts by some ovarian cancers. Doctors may use CA125 blood tests monitor recurrence or response to treatment. 

Clinical trials are studying whether other blood tests known as liquid biopsies can be used to detect recurrence in people who have completed treatment for ovarian cancer.  These tests check the blood for abnormal DNA from tumor cells (known as circulating tumor DNA or ctDNA).