The objective of surgery is to completely remove the primary tumor, while minimizing treatment-related morbidity, and to guide postoperative treatment with radioactive iodine (RAI). The goal of RAI is to ablate the remnant thyroid tissue to improve the specificity of thyroglobulin assays, which allows the detection of persistent disease by follow-up whole-body scanning. For patients undergoing RAI, removal of all normal thyroid tissue is an important surgical objective. Additionally, for accurate long-term surveillance, RAI whole-body scanning and measurement of serum thyroglobulin are affected by residual, normal thyroid tissue, and in these situations, near total or total thyroidectomy is required. This approach facilitates follow-up thyroid scanning.
I131: Studies have shown that a postoperative course of therapeutic (ablative) doses of I131 results in a decreased recurrence rate among high-risk patients with papillary and follicular carcinomas. It may be given in addition to exogenous thyroid hormone but is not considered routine. Patients presenting with papillary thyroid microcarcinomas (tumors <10 mm) have an excellent prognosis when treated surgically, and additional therapy with I131 would not be expected to improve the prognosis.
Thyroid lobectomy alone may be sufficient treatment for small (<1 cm), low-risk, unifocal, intrathyroidal papillary carcinomas in the absence of prior head and neck irradiation or radiologically or clinically involved cervical nodal metastases. This procedure is associated with a lower incidence of complications, but approximately 5% to 10% of patients will have a recurrence in the thyroid following lobectomy. Patients younger than 45 years will have the longest follow-up period and the greatest opportunity for recurrence. Follicular thyroid cancer commonly metastasizes to lungs and bone; with a remnant lobe in place, use of I131 as ablative therapy is compromised. Abnormal regional lymph nodes should be biopsied at the time of surgery. Recognized nodal involvement should be removed at initial surgery, but selective node removal can be performed, and radical neck dissection is usually not required. This results in a decreased recurrence rate but has not been shown to improve survival.
Following the surgical procedure, patients should receive postoperative treatment with exogenous thyroid hormone in doses sufficient to suppress thyroid-stimulating hormone (TSH); studies have shown a decreased incidence of recurrence when TSH is suppressed.