Follicular cell-derived thyroid cancer

Follicular cell-derived thyroid cancers are derived from the follicular cells in the thyroid gland, which secrete the iodine-containing thyroid hormones. Follicular cell-derived thyroid cancers can be classified into papillary thyroid cancer (80-85%), follicular thyroid cancer (10-15%), poorly differentiated thyroid cancer (<2%) and undifferentiated (anaplastic) thyroid cancer (<2%), and these have an excellent prognosis with the exception of undifferentiated thyroid cancer. The advent and expansion of advanced diagnostic techniques has driven and continues to drive the epidemic of occult papillary thyroid cancer, owing to overdiagnosis of clinically irrelevant nodules. This transformation of the thyroid cancer landscape at molecular and clinical levels calls for the modification of management strategies towards personalized medicine based on individual risk assessment to deliver the most effective but least aggressive treatment. In thyroid cancer surgery, for instance, injuries to structures outside the thyroid gland, such as the recurrent laryngeal nerve in 2-5% of surgeries or the parathyroid glands in 5-10% of surgeries, negatively affect quality of life more than loss of the expendable thyroid gland. Furthermore, the risks associated with radioiodine ablation may outweigh the risks of persistent or recurrent disease and disease-specific mortality. Improvement in the health-related quality of life of survivors of follicular cell-derived thyroid cancer, which is decreased despite the generally favourable outcome, hinges on early tumour detection and minimization of treatment-related sequelae. Future opportunities include more widespread adoption of molecular and clinical risk stratification and identification of actionable targets for individualized therapies.

Clinical features and genetic predisposition to hereditary nonmedullary thyroid cancer

BACKGROUND

Approximately 5% of the nonmedullary thyroid cancers are hereditary. Hereditary nonmedullary thyroid cancer may occur as a minor component of familial cancer syndromes (familial adenomatous polyposis, Gardner's syndrome, Cowden's disease, Carney's complex type 1, Werner's syndrome, and papillary renal neoplasia) or as a primary feature (familial nonmedullary thyroid cancer [FNMTC]). The goal of this article was to review our current knowledge on the hereditary nonmedullary thyroid cancer.

SUMMARY

Epidemiologic and clinical kindred studies have demonstrated that FNMTC is a unique clinical entity. Most studies suggest that FNMTC is associated with more aggressive disease than sporadic cases, with higher rates of multicentric tumors, lymph node metastasis, extrathyroidal invasion, and shorter disease-free survival. A hereditary predisposition to nonmedullary thyroid cancer is well established, but the susceptibility genes for isolated FNMTC have not been identified. However, additional susceptibility loci for FNMTC have been recently identified in classic isolated cases of FNMTC (1q21, 6q22, 8p23.1-p22, and 8q24).

CONCLUSIONS

More studies are needed to validate chromosomal susceptibility loci and identify the susceptibility genes for FNMTC. The discovery of the predisposing genes may allow for screening and early diagnosis, which could lead to improved outcomes for patients and their families.