Treatment

There are strong proponents of near-total or total thyroidectomy, although the extent of thyroid surgery remains controversial.

It has recently been demonstrated that near-total or total thyroidectomy results in lower recurrence rates and improved survival for papillary thyroid cancer greater or equal than 1 cm compared with lobectomies.^[1]

Near-total or total thyroidectomy, may, however, increase the risk of surgical complications.^[2,3] Unilateral lobectomy is sometimes performed in younger, low risk patients as classified by AMES.^[4] However, performing a lobectomy has been associated with an increased recurrence rate in the opposite lobe and an increased incidence of subsequent pulmonary metastases.^[5,6] Furthermore, total removal of the thyroid gland makes whole body scan (WBS) and thyroglobulin (Tg) testing easier to interpret throughout the patient’s regular lifelong follow-up to rule out or detect recurrence.

Following surgery, radioiodine therapy allows for the ablation of any residual thyroid tissue to remove the thyroid remnant thereby facilitating patient long term follow-up and prevent recurrence. Selective use of postoperative radioiodine therapy in patients with high risk of recurrence can decrease recurrence and death rates. However, in certain very low risk patients, the use of radioiodine therapy may not be warranted in light of possible side effects such as radiation thyroiditis, radiation cystitis, and potential carcinogenic risk.^[2,3]

Patients require proper stimulation to increase TSH levels and thus enhance uptake of radioiodine into the thyroid tissues.

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.^[1]

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.

Long-term management with thyroid hormone therapy (THT) has demonstrated a beneficial effect on survival and recurrence^[7] in thyroid cancer patients who have undergone thyroidectomy. Thyroid cancer cells depend in part on thyroid-stimulating hormone (TSH) for growth. Suppressing endogenous TSH through the administration of supraphysiologic doses of thyroid hormone, most often using thyroxine [T4], is thought to deprive these cells of an important growth-promoting influence.^[8] Traditionally, the goal of THT has been complete suppression of pituitary secretion of TSH, as indicated by undetectable levels of serum TSH when measured in sensitive immunometric assays.^[8]

After a patient has been followed for a time and found by Thyrogen or other testing to be at very low risk for having residual tumor, it may be acceptable to lower the dose of thyroxine to allow the patient’s serum TSH level to rise into the detectable range; this may lower the patient’s risk for complications that might occur during years of chronic mild hyperthyroidism, such as osteopenia or cardiac arrhythmias.^[9]

REFERENCES:

1. Billimoria KY, Extent of Surgery Affects Survival for Papillary Thyroid Cancer, Annals of Surgery, Volume 246, #3, September 2007

2. Schlumberger MJ. Papillary and follicular thyroid carcinoma. N Engl J Med. 1998;338:297-306.

3. Fuchshuber P, Loree TR, DeLacure MD, et al. Differentiated thyroid carcinoma: risk group assignment and management controversies. Oncology. 1998;12:99-106.

4. Cady B, Hay ID, Shaha AR, Clark OH, et al. Unilateral total lobectomy: Is it sufficient surgical treatment for patients with AMES low-risk papillary carcinoma? Discuss Surg. 1998; 124:964-966

5. Mazzaferri EL. Thyroid carcinoma. Papillary and Follicular. In: Mazzaferri EL, Samaan N, eds.

Endocrine tumors. Cambridge: Blackwell scientific Publications Inc.; 1993: 278-333.

6. Massin JP, Savoie JC, Garnier H, Guirandron G, et. Al. Pulmonary metastases in differentiated thyroid carcinoma. Study of 58 cases with implications for primary tumor treatment. Cancer. 1984:53:982-992

7. Mazzaferri EL, Kloos RT, Current approaches to primary therapy for papillary and follicular thyroid cancer.J Clin Endocrinol Metab. 2001;86:1447-1463

8. AACE/AAES medical/surgical guidelines for clinical practice: management of thyroid carcinoma. American Association of Clinical Endocrinologists. American College of Endocrinology. Endocr Pract 2001;7(3):202-20.

9. American Thyroid Association Guidelines Taskforce. Management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid 16 (2): 109-141, 2006.