Radioactive iodine scintigraphy is a common method used to detect thyroid cancer cells in the body. It is most often used after surgery to find any remaining cancer cells, and is particularly useful for papillary and follicular thyroid cancers. The only way to confirm if a lump in the thyroid is cancer is through a biopsy, where a small sample of cells is removed and studied under a microscope. In most cases, microscopic analysis of cells obtained from a needle biopsy can easily determine if a nodule is benign (not cancerous) or malignant (cancer).
Thyroid blood tests are usually done to assess thyroid function, and an ultrasound of the thyroid is often done to assess the structure of the thyroid gland, but neither of these types of tests is sufficient to determine with confidence whether a thyroid nodule is benign or malignant. Thyroglobulin (Tg) is a protein naturally produced by the thyroid, as well as by differentiated thyroid cancer. It can be used to identify abnormal areas of the thyroid gland or to determine if cancer has spread to other areas of the body. Abnormal levels could mean you have an overactive or underactive thyroid, rather than cancer.
Your doctor will use this test to determine the current levels of the thyroid hormones triiodothyronine (T) and thyroxine (T) in your body. CT scans are often used in people with thyroid cancer to examine parts of the neck that cannot be seen with an ultrasound. In addition, CT scans of the chest may be needed to see if thyroid cancer has spread to that area of the body, and CT scans of the abdomen may be used to see if it has spread to the liver or other sites. Molecular testing of the nodule sample can help you understand the risk that the thyroid nodule is cancerous.
Other genetic, protein, and molecular analysis of thyroid cancers can help determine treatment options, including types of treatments called targeted therapy. Radioactive iodine can also be used to treat differentiated thyroid cancer, but it is given in much higher doses. If surgery is recommended, the larynx can be examined at the same time with a laryngoscope, which is a thin, flexible tube with a light. If the needle aspiration biopsy is not clear, the doctor may suggest a biopsy in which the nodule and possibly the affected thyroid lobe will be removed by surgery. Removal of the nodule alone is generally not recommended because of the possibility of completely removing the potentially cancerous tumor without sufficient margins, which is an area of tissue around the nodule. This procedure is usually performed under general anesthesia and may also require hospitalization.
A whole-body scan using a very small and harmless amount of radioactive iodine I-131 or I-123 can be done to learn more about a thyroid nodule. In this test, the patient ingests the marker, which is taken up by thyroid cells. This causes thyroid cells to appear on the scan image, allowing the doctor to see the differences between these cells and other structures in the body. If you are diagnosed with thyroid cancer during pregnancy, your healthcare provider can discuss treatment options. Your multidisciplinary team will work with you to develop a personalized plan to treat thyroid cancer in a way that fits your individual needs and goals.