Head & Neck Cancer
Genomic Testing
For a long time, treating head and neck cancers has been largely dominated by surgery and radiation therapy. But, now, new treatment options may be available to target specific biomarkers found through genomic testing. Several biomarkers have already been identified in some head and neck cancers, with more likely to be discovered in the future. These help doctors provide more personalized patient care.
The Role of Mutations
Just as every person has a specific mix of genes that is unique to them, cancers are driven by a mixture of specific mutations (changes that occur in the DNA of a cell). Genomic testing is specialized testing that identifies the presence or absence of cancer-causing mutations. It allows doctors to learn about a tumor’s genome, which is a complete set of its DNA. By unlocking the DNA code of the tumor, doctors can better understand its unique characteristics.
To learn how genomic testing is used in head and neck cancer, it is important to understand biomarkers. They are substances, such as genes and molecules, which are produced by cancer cells or other cells of the body in response to cancer. They can be measured in the blood, plasma, urine, cerebrospinal fluid or other body fluids or tissues. They are also known as tumor markers or biological markers. Testing for biomarkers is also known as molecular testing.
The goal of this testing is to provide the tools your medical team needs to personalize your treatment. In cases where your doctor determines it has a clinical benefit, some of the potential uses include the following:
- Diagnosing and staging a cancer
- Determining prognosis (outlook)
- Predicting how the tumor might behave, such as how fast growing it is and how likely it is to metastasize (spread)
- Evaluating whether therapies are available to treat mutations in that specific cancer
- Choosing treatment
- Monitoring treatment effectiveness
- Watching for progression or recurrence
Even if testing is performed, keep in mind that the test results will not provide a solution in every case. Not every tumor has known mutations, and some are identified that do not yet have a specialized treatment. In addition, not all cancer centers offer molecular testing, so it is important to find out whether it has been performed on your blood or tissue samples. If it was, ask your doctor to explain which biomarkers were tested for and the results.
Understanding the types of mutations your tumor has will help you make informed decisions with your doctor about your treatment options. If a mutation is found, your doctor will determine whether the testing indicates you are a candidate for immunotherapy or targeted therapy.
Biomarkers for Head and Neck Cancer
With head and neck cancers, biomarkers are most often tested during the diagnosis and staging process but may also be checked for when a tumor returns because it may have different mutations than before. It is also recommended to test for biomarkers if the cancer is recurrent or metastatic.
Some of the biomarkers that may be tested for in head and neck cancer include the following:
Epstein-Barr virus (EBV) is associated with some nasopharyngeal cancers and may be tested to help make a diagnosis as well as assess the response of therapy and monitor for recurrence. It is believed that after an infection with EBV, some of the virus’ DNA mixes with the DNA of cells in the nasopharynx (upper part of the throat) and is able to divide and grow abnormally. Genomic testing can detect the virus in tumor cells or in the blood.
Human papillomavirus (HPV) is primarily tested with throat cancers as a part of the staging process. It has specific subtypes that are linked to throat cancers, specifically oropharyngeal cancer. Research is still determining whether HPV is a biomarker for any of the other types of head and neck cancer. Determining a patient’s HPV status can provide prognostic information and place patients into risk categories. Some doctors will do a blood test for circulating tumor tissue-modified viral (TTMV) HPV DNA, which may be used to monitor patients post-treatment for a possible recurrence.
Genes may be tested to determine a patient’s eligibility to receive certain types of targeted therapy. Currently, therapies are approved for people with abnormalities in the BRAF, RET, p53 and NTRK genes.
Programmed cell death-ligand 1 (PD-L1) helps determine whether a patient is likely to respond to immunotherapy.
Proteins and growth factors affect how tumor cells develop and survive. They are tested to determine whether a person has abnormalities in the vascular endothelial growth factor (VEGF), epidermal growth factor receptor (EGFR) and the MEK protein. A type of targeted therapy known as a tyrosine kinase inhibitor (TKI) is available to treat these abnormalities.
Thyroid hormone levels, such as thyroglobulin, thyroid-stimulating hormone, thyroglobulin antibodies, and medullary type-specific tests, which include calcitonin and carcinoembryonic antigen (CEA) levels, are biomarkers for thyroid cancer. It is recommended that you are tested for mutations in the RET gene if you have a family history of medullary thyroid cancer.
Tumor mutational burden (TMB) is the total number of mutations (changes) found in the DNA of cancer cells. Tumors that have a high number of mutations appear to be more likely to respond to certain types of immunotherapy.
Other biomarker-based treatment strategies are being tested in clinical trials.
