Most people with thyroid cancer are treated successfully with thyroid surgery followed by radioactive iodine therapy. In the years following this successful treatment, about one third of patients may experience a recurrence of thyroid cancer, usually in lymph nodes in the neck, and less frequently in the lungs. Much of the focus of our follow-up visits and tests is on the early detection of these recurrences.

In addition to the standard imaging studies (such as neck ultrasound), tests are available that take advantage of the unique ability of thyroid cancer cells to concentrate radioactive iodine and to secrete thyroglobulin. If all normal and malignant thyroid cells are destroyed by thyroidectomy and radioactive iodine therapy, the serum thyroglobulin should be low or undetectable and the radioactive iodine scan should be negative.

For many years, we have understood that it is easier to detect metastatic thyroid cancer cells if they are stimulated by TSH (thyroid stimulating hormone) for a short period just before performing radioactive iodine scanning and measuring the serum thyroglobulin. Until the advent of Thyrogen (rhTSH), it was necessary to discontinue all thyroid hormone medications for several weeks so that the normal pituitary would make more TSH and stimulate the thyroid cancer cells. Stopping thyroid hormone pills resulted in symptoms for many patients including tiredness, fatigue, weight gain, and poor memory.

Today, we use Thyrogen to stimulate the thyroid cells for radioactive iodine scanning and serum thyroglobulin measurements. Because it is not necessary to discontinue thyroid hormone pills, patients do not experience the classic symptoms of under active thyroid described above. Thyrogen injections resulted in a short period of intense stimulation of thyroid cells which allows for easy detection of recurrence.

Following the Thyrogen injections, some patients suffer from nausea, headaches, weakness, or vomiting. Some have experienced tingling sensations. You should also be aware of several reports of mild hypersensitivity including rash and flushing after Thyrogen injections. Please refer to the full prescribing information (PDF).

In addition to Thyrogen stimulation, we advise all of our patients to follow a low-iodine diet for a week before radioactive iodine scanning. Since Thyrogen is stimulating the uptake of iodine into the thyroid cell, we want to maximize the uptake of radioactive iodine and minimize the uptake of normal iodine that is present in iodized salt, seafood, and many dairy products.

Determining which tests to use in the long-term monitoring of patients with differentiated thyroid cancer involves assessing the risk of your patients for recurrent disease. Risk factors include patient history, age, gender, histology, initial treatment, invasiveness, tumor size and results of previous tests.

Diagnostic whole body scanning - for many years the primary monitoring tool - by itself misses about one-third of the cases of residual disease.^[1] Stimulated Tg has been shown as more accurate in the detection of disease than WBS after TSH stimulation accomplished by either stopping thyroid hormones or by injections of Thyrogen. However, analysis of both tests together almost always results in better diagnostic accuracy than either test alone. With Thyrogen, there remains a risk of missing detection or underestimating the extent of disease for patients of all risk categories. Therefore, determine the risk of your patient before selecting test modalities.

For many years, follow-up testing generally included both radioactive iodine whole body scanning and serum thyroglobulin measurements. In many of our low risk patients, especially those who have had one previous negative radioactive iodine whole body scan, the primary follow-up is done using Thyrogen-stimulated serum thyroglobulin. Repeat radioactive iodine scanning is recommended if there is suspicion for recurrent disease either on routine imaging studies (such as neck ultrasound) or if the stimulated serum thyroglobulin rises inappropriately. For more information, see the safety information below.