After thyroid surgery, some patients may require a second step in the initial treatment of thyroid cancer. This step is called thyroid remnant ablation. The thyroid remnant is any remaining thyroid tissue that the surgeon was not able to remove during the thyroidectomy. Thyroid remnant ablation is not recommended for all patients; this will depend upon risk factors such as tumor size.
Thyroid remnant ablation is performed by giving you a dose of radiation in the form of a capsule or liquid. This is called radioactive iodine which targets and destroys any remaining thyroid tissue or cells that may be present in the body. These cells may be normal thyroid cells, cancerous thyroid cells, or both. This procedure is usually done several weeks after the thyroidectomy.
For the radioactive iodine to be taken into the thyroid cells effectively, the patient needs to have an elevated thyroid stimulating hormone (TSH) level. This elevation can be accomplished by taking the patient off their thyroid hormone therapy; however, the patient will then experience the symptoms and effects of hypothyroidism. In December 2007, another option for increasing the TSH levels for purposes of ablation was approved by the FDA. Thyrogen (rhTSH) was approved for use as an adjunct treatment for radioiodine ablation of thyroid tissue remnants in patients who have undergone a near-total or total thyroidectomy for well-differentiated thyroid cancer. Using Thyrogen allows a patient to continue on their thyroid hormone therapy, avoiding the symptoms and effects of hypothyroidism when undergoing remnant ablation. Thyrogen is delivered in 2 injections prior to the thyroid remnant ablation procedure. Both methods of increasing TSH, withholding thyroid hormone therapy or using Thyrogen, have shown comparable success rates in thyroid remnant ablation.
There is currently one option that allows you to stay on your thyroid hormone therapy in preparation for thyroid remnant ablation:
Thyrogen®, (thyrotropin alfa for injection), a version of TSH manufactured by biotechnology that is similar to the TSH that your body naturally produces. Using Thyrogen allows a patient to continue on their thyroid hormone therapy in preparation for thyroid remnant ablation. Thyrogen must be prescribed by your doctor. Go to About Thyrogen for more information
- American Thyroid Association Guidelines Taskforce. Management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid 16 (2): 109-141, 2006. See the ATA Guidelines.