How is follicular thyroid carcinoma (FTC) treated?

Updated: Jun 18, 2020
  • Author: Luigi Santacroce, MD; Chief Editor: Neetu Radhakrishnan, MD  more...
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Answer

The initial treatment for cancer of the thyroid is surgical. The exact nature of the surgical procedure to be performed depends for the most part on the extent of the local disease. A consensus approach might be to perform a total thyroidectomy if the primary tumor is larger than 1 cm in diameter or if there is extrathyroidal involvement or distant metastases. Clinically evident lymphadenopathy should be removed with a neck dissection. If the primary tumor is less than 1 cm in diameter, a unilateral lobectomy might be considered.

Current National Comprehensive Cancer Network (NCCN) guidelines recommend lobectomy plus isthmusectomy as the initial surgery for patients with follicular neoplasms, with prompt completion of thyroidectomy if invasive follicular thyroid carcinoma (FTC) is found on the final histologic section. Therapeutic neck dissection of involved compartments is recommended for clinically apparent/biopsy-proven disease. [1]

The NCCN recommends total thyroidectomy as the initial procedure only if invasive cancer or metastatic disease is apparent at the time or surgery, or if the patient wishes to avoid a second, completion thyroidectomy should the pathologic review reveal cancer. [1]

About 4-6 weeks after surgical thyroid removal, patients must have radioiodine to detect and destroy any metastasis and any residual tissue in the thyroid. Administer therapy until no further radioiodine uptake is noted.

Patients take thyroid replacement therapy (ie, levothyroxine [L-T4]) for life. This entails taking 2.5-3.5 mcg/kg of L-T4 every day. The thyroxine is given in the dose necessary to inhibit thyrotropin to a value of 0.1-0.5 mU/L. This treatment plan is generally successful. However, a 10-year recurrence rate of 20-30% may be seen in older patients, in patients with primary tumors greater than 4 cm in diameter, and in patients where tumor has spread beyond the thyroid boundaries and where lymph node involvement is widespread. Once metastatic thyroid cancer becomes resistant to radioiodine, the 10-year survival is less than 15%.

A number of indications for external beam radiation therapy (EBRT) apply to the management of FTC. If all gross disease cannot be resected, or if residual disease is not avid for radioactive iodine, EBRT is often employed for locally advanced disease.

Similarly, radiation therapy is indicated for unresectable disease extending into adjacent structures, such as the trachea, esophagus, great vessels, mediastinum, and/or connective tissue. In this situation, radiation therapy doses of 6000-6500 cGy are typically used. Following radiation therapy for unresectable disease, the patient should undergo radioactive iodine (I-131) scanning. If uptake is detected, a dose of I-131 should be administered.

EBRT increases the local-regional control of the residual disease for patients with locally advanced differentiated thyroid carcinoma. [24] EBRT also may be used after resection of recurrent FTC that is no longer avid for radioactive iodine.

In the postoperative setting, radiation therapy doses of 5000-6000 cGy are commonly delivered to the tumor bed to reduce the risk of local-regional recurrence.

Careful treatment planning (typically with multiple radiation therapy fields) should be employed to minimize the risks of radiation therapy complications.

Finally, a palliative course of radiation therapy is useful to relieve pain from bone metastases.

Chemotherapy with cisplatin or doxorubicin has limited efficacy, producing occasional objective responses (generally for short durations). Because of the high toxicity of cisplatin and doxorubicin, chemotherapy may be considered in symptomatic patients with recurrent or progressive disease. It could improve quality of life in patients with bone metastases. No standard protocol exists for chemotherapy of metastatic FTC.

FTC is a highly vascular lesion. In patients with bone metastases who experience severe pain that does not respond to palliative radiation, arterial embolization of the tumor might be considered.

The possible involvement of angiogenesis in the progression of metastatic thyroid carcinoma has suggested a role for the multikinase inhibitor sunitinib, which may inhibit angiogenesis. A phase II trial in 23 patients with advanced differentiated thyroid cancer who had received at least one course of radioactive iodine treatment demonstrated that sunitinib exhibits significant anti-tumor activity. Of the 23 patients, six (26%) achieved a partial response and 13 (57%) had stable disease. [25]

See Thyroid Cancer Treatment Protocols for summarized information.


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