Thyroid Cancer Treatment (PDQ®): Treatment - Health Professional Information [NCI] - Stage I and II Papillary and Follicular Thyroid Cancer
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.
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. For optimal treatment with RAI, total thyroidectomy is recommended with minimal thyroid remnant remaining. With a large thyroid remnant, a low thyroglobulin level cannot be achieved, which increases the chance of requiring multiple doses of RAI.
Consideration of RAI for remnant ablation is based on pathological risk features including:
- Evaluation of the size of the primary tumor.
- The presence of lymphovascular invasion.
- Capsule invasion.
- The number of involved lymph nodes.
RAI may be given with one of two methods of thyrotropin stimulation: withdrawal of thyroid hormone or recombinant human thyrotropin (rhTSH). Administered rhTSH maintains quality of life and reduces the radiation dose delivered to the body compared with thyroid hormone withdrawal. Patients presenting with papillary thyroid microcarcinomas (tumors <10 mm), which are considered to be very low risk, have an excellent prognosis when treated surgically, and additional therapy with I131 would not be expected to improve the prognosis.
The role of RAI in low-risk patients is not clear because disease-free survival (DFS) or overall survival (OS) benefits have not been demonstrated. One study reviewed 1,298 patients from the French Thyroid Cancer Registry. Patients were identified as having low-risk papillary or follicular cancer as they are defined by the American Thyroid Association and the European Thyroid Association criteria:
- Complete tumor resection.
- Multifocal pT1 <1 cm.
- pT1 >1 cm.
- pT2, pN0, pM0 (American Joint Committee on Cancer/Union Internationale Contre le Cancer [AJCC/UICC]) corresponds to stage I for patients <45 years old.
- pT2, pN0, pM0 (AJCC/UICC) corresponds to stages 1 and 2 for patients >45 years old.
- pT1 and pT2 without lymph node dissection (Nx).