Serology, also known as blood serum testing, can determine the levels of relevant biomarkers in the blood. Biomarkers provide information about the presence of a disease.
While serology is less often used for head and neck cancers than it is for other forms of cancer, it does offer advantages for diagnosing and monitoring nasopharyngeal and thyroid cancer. These cancers have unique biomarkers associated with their presence. Checking the levels of these relevant biomarkers throughout your course of treatment can allow the physician to determine the status of the cancer.
Nasopharyngeal Cancer Biomarkers
In nasopharyngeal cancer, doctors may order blood tests to check for the presence of Epstein-Barr Virus (EBV), which is often associated with cancers in this region. Both the DNA of the virus and antibodies to the virus made by the patient’s immune system can be measured. These blood tests can be used for nasopharyngeal cancer detection, as well as for monitoring the body’s response to treatment and surveillance after treatment.
Thyroid Cancer Biomarkers
Throughout the diagnosis, treatment, and follow-up of thyroid cancer, patients will likely undergo many blood tests to measure the levels of several different hormones and proteins. These test results help doctors understand disease progress and determine appropriate solutions. Below you will find a list of relevant biomarkers for thyroid cancer, specifically.
Thyroid Stimulating Hormone (TSH) Levels
- TSH is a hormone produced in the brain by the pituitary gland. It plays a role in maintaining hormone balance and stimulating growth of thyroid tissue.
- TSH levels are very important to monitor for all types of thyroid disease.
TSH is a hormone produced by the pituitary gland in the brain. It stimulates the growth of thyroid tissue and signals the thyroid gland to absorb more iodine and produce more thyroid hormone. TSH regulates the thyroid gland in order to maintain a hormone balance.
When a patient is first diagnosed with a thyroid nodule, generally on imaging, their TSH levels will be checked to determine if they are high, low, or normal. If a patient’s TSH levels are high or normal (and the nodule has suspicious characteristics on ultrasound), the patient will likely get a biopsy. If the patient’s TSH levels are low, they will undergo an RAI uptake scan.
TSH levels are generally measured at 3–4 weeks following surgery to evaluate the amount of thyroid hormone replacement that the patient will need following surgery. Finding the right dosage of thyroid hormone replacement after surgery is essential. Treatment with thyroid hormone is important for two main reasons. Firstly, since some or all of the thyroid gland has been removed, this therapy helps restore the thyroid hormone levels in the body. Secondly, thyroid hormone therapy keeps TSH levels low, which helps to reduce the risk of disease recurrence. TSH suppression is part of the post-treatment strategy for thyroid cancer patients that is used to avoid the growth of any residual thyroid cancer cells and prevent recurrence. Learn more about TSH suppression.
TSH will be monitored periodically (every 3–6 months) after initial treatment to assess whether the current thyroid hormone dose is adequate for the patient.
Free Thyroxine (T4) Levels
The thyroid gland produces T4 which regulates metabolism and other bodily functions. High levels of T4 indicate an overactive thyroid, while low levels indicate an underactive thyroid. Dysregulation of T4 levels is common in thyroid cancers.
Thyroglobulin (Tg) Levels
Thyroglobulin (Tg) is a protein found in thyroid tissue, which is an essential ingredient for thyroid hormone production. Normally, Tg drops significantly in patients after a total thyroidectomy and RAI treatment. Therefore, any elevation in Tg levels following treatment is considered to be an indicator of disease recurrence or progression. A rise in Tg levels will signal doctors to order additional diagnostic studies, and may mean that additional treatment will be necessary. Initially serum Tg should be measured every 6–12 months, or more frequently if you are a high-risk patient.
Tg levels 3-4 weeks after surgery are generally used to predict disease recurrence, and to decide if additional treatment with RAI is needed.
Thyroglobulin Antibody (TgAb) Levels
Thyroglobulin Antibody (TgAb) can react with Tg in the blood. Due to these interactions, high levels of TgAb may produce inaccurate results for Tg levels. Inaccurate lab results for Tg levels may interfere with a doctor’s diagnosis of disease recurrence or progression. It is important to measure these levels simultaneously to ensure a comprehensive assessment of the results.
TSH, Tg, and TgAb levels will all be measured at the same time to allow doctors to accurately assess the results.
If Medullary Thyroid Cancer (MTC) is suspected preoperatively, doctors may order additional blood tests, specifically for calcitonin and carcinoembryonic antigen (CEA). A baseline level of these blood markers will be tested before treatment, and both calcitonin and CEA levels will be monitored during and after treatment .
Calcitonin Levels
C-cells (parafollicular cells) are found in the thyroid gland and produce the hormone calcitonin. The role of calcitonin is to help regulate blood calcium and phosphate levels. Elevated calcitonin levels can signal to a physician that something is abnormal. Typically, increased calcitonin levels are associated with medullary thyroid cancer (MTC) because it originates in the C-cells.
Carcinoembryonic Antigen (CEA) Levels
Carcinoembryonic antigen (CEA) is a blood marker that is typically only present during fetal development, but production falls to almost zero before birth. In healthy adults, the levels of CEA in the blood are extremely low. However, blood levels of CEA have been shown to increase in certain cancers, particularly in medullary thyroid carcinoma.
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