Thyroid Cancer - Treatment Options (Papillary and Follicular)
Written by Monique Atkinson and endorsed by Dr Hieu Nguyen
Surgery -Thyroidectomy or Lobectomy
Most patients with thyroid cancer have a total thyroidectomy (removal of the thyroid gland), but a small percentage of patients may only have a lobectomy (removal of one lobe). Sometimes cancerous lymph nodes in the neck are removed as well. If only one lobe is removed, then the residual thyroid gland may or may not produce enough thyroid hormone. When the whole thyroid gland is removed, the patient will be on full thyroid hormone replacement therapy for life.
Any surgery on the thyroid gland should be done by an experienced surgeon who performs high volume surgery on the thyroid to minimize adverse outcomes. This is usually done by an endocrine surgeon. However patients are sometimes referred to a general surgeon, who may not have as much experience with surgery on the thyroid gland. Behind the thyroid gland are four small parathyroid glands and it is preferable to preserve their function. If the parathyroid glands are damaged, calcium levels will drop. Approximately 20 % of patients experience a transient drop of calcium. However, only 1 % of patients develop permanent hypoparathyroidism (underactive parathyroid glands). The thyroid gland is also located close to the nerves that control the voice box (called recurrent laryngeal nerves). The risk to impaired nerve function (voice impairment) is also about 1%.
Radioactive Iodine Treatment - Thyroid Remnant Ablation
Radioactive iodine treatment may be used after a thyroidectomy or near total thyroidectomy, which will destroy any remaining thyroid cells (including normal and cancerous cells). The size of the remnant is quite small when surgery is performed by high volume surgeons. This treatment is also referred to as thyroid remnant ablation. Thyroid cells that have spread to other parts of the body will be destroyed as well. The dose of radiation (the radioactive iodine) is given either in a capsule or a liquid. Not all patients will need this treatment.
For the radioactive iodine to effectively destroy any remaining thyroid cells (either normal or cancerous), the TSH (thyroid stimulating hormone) has to be high. This encourages the cells to take up the maximum amount of radioactive iodine.
There are two ways in which you can achieve a high TSH;
- After the thyroidectomy you have to wait for about 4 to 6 weeks until your TSH has reached a high level. So the weeks following surgery you will become severely hypothyroid and you may suffer physically, mentally & emotionally. Some doctors prescribe Tertroxin (T3) for the first few weeks, then stop the Tertroxin for 3 weeks by which time the TSH has increased enough. T3 is given, because it has a shorter half life in the body (disappears faster from the body). It is also recommended that you eat foods that are low in iodine in the weeks leading up to the treatment and for about one week after treatment. This way any remaining thyroid cells are more likely to take up the iodine during the treatment, because the cells have been deprived of iodine.
- There is also a drug available that can increase the TSH to a high level within two days, called Thyrogen. When Thyrogen is used, the patients can continue thyroid hormone replacement therapy, without suffering from the mental and physical effects of hypothyroidism. A low iodine diet is still recommended for about two weeks.
Thyrogen is a synthetic TSH (recombinant TSH). Thyrogen (thyrotropin alfa powder for injection) is an authority script that can be used under the following condition;
"3193 - Ablation of thyroid remnant tissue, in combination with radioactive iodine, in a post thyroidectomy patient without known metastatic disease" (Pharmaceutical Benefits Scheme 2011)
In Western Australia, radioactive iodine treatment for thyroid cancer patients is only administered in approved hospitals. You receive the treatment in a hospital room which has lead lined walls and a bathroom, where you need to stay in isolation. You cannot leave the room until the radiation level in your body is safe for other people. A urine test is used to check your radiation level. Drinking plenty of water will help shorten your stay. When you are allowed to go home, you still need to avoid close contact with other people for one more week (you need to keep a safe distance of two metres from other people and pets). After the radioactive iodine treatment, thyroglobulin levels and its antibodies will be measured. These levels are useful markers for ongoing monitoring. Unfortunately thyroid cancers can return, so it may be necessary to receive subsequent radioactive iodine treatments.
Thyroid Hormone Replacement Therapy
After the treatment you will need to take thyroid hormone replacement therapy for life to replace the hormones normally produced by the thyroid. We cannot live without thyroid hormone. Initially the endocrinologist will aim for a TSH which is suppressed to prevent the growth of any cancer cells which may still reside in the body. Suppression therapy is recommended for both papillary and follicular cancer, but not for medullary cancer and anaplastic cancer. It is recommended that you see an endocrinologist who has experience in the management of thyroid cancer.
Algorithm for follow-up after treatment of differentiated thyroid cancer
T4 = thyroxine. TSH = thyroid stimulating hormone. * Achieved by discontinuing thyroid replacement therapy for 1 month. Recombinant TSH has a potential role. † To detect non-iodine-avid disease
"MacKenzie EJ and Mortimer RH. 6: Thyroid Nodules and Thyroid Cancer. MJA 2004; 180: 242-247. © Copyright 2004. The Medical Journal of Australia - reproduced with permission"