What is follicular thyroid carcinoma (FTC)?

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

Follicular thyroid carcinoma (FTC) is the second most common cancer of the thyroid, after papillary carcinoma. Follicular and papillary thyroid cancers are considered to be differentiated thyroid cancers; together they make up 95% of thyroid cancer cases.

FTC and other thyroid neoplasms arising from follicular cells (adenomas, papillary/follicular carcinoma, and noninvasive follicular thyroid neoplasm with papillary-like nuclear features [NIFTP]) show a broad range of overlapping clinical and cytologic features. FTC resembles the normal microscopic pattern of the thyroid, and a clear distinction between benign and malignant disease based solely on cytological examination of a needle biopsy specimen may be difficult.

For this reason, a surgical procedure to remove all or a large portion of the thyroid gland may be necessary to obtain sufficient tissue for a definitive diagnosis of FTC. Pathological examination showing capsular or vascular invasion may be required for this determination.

Papillary/follicular carcinoma must be considered a variant of papillary thyroid carcinoma (mixed form). Hurthle cell carcinoma should be considered a variant of FTC.

Despite its well-differentiated characteristics, FTC may be overtly or minimally invasive. In fact, FTC tumors may spread easily to other organs. About 11% of patients with FTC have metastases beyond the cervical or mediastinal area on initial presentation

Life expectancy of affected patients is related to their age; the prognosis is better for younger patients than for patients who are older than 45 years. Patients with FTC are more likely to develop lung and bone metastases than are patients with papillary thyroid cancer. The bone metastases in FTC are osteolytic. Older patients have an increased risk of developing bone and lung metastases.

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 FTC is found on the final histologic section. Therapeutic neck dissection of involved compartments is recommended for clinically apparent/biopsy-proven disease. The NCCN recommends total thyroidectomy as the initial procedure only if invasive cancer or metastatic disease is apparent at the time of surgery, or if the patient wishes to avoid a second, completion thyroidectomy should the pathologic review reveal cancer. [1]

If all gross disease cannot be resected, or if residual disease is not avid for radioactive iodine, radiation therapy is often employed for locally advanced disease. Similarly, radiation therapy is indicated for unresectable disease extending into adjacent structures. Chemotherapy may be considered in symptomatic patients with recurrent or progressive disease. It could improve quality of life in patients with bone metastases.

For patient education information, see the Thyroid Cancer Directory. Patient education information on thyroid cancer is also available on the American Cancer Society Web site.


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