Head and neck cancer

Head and Neck Cancers:
Differentiated Thyroid
Cancer

Differentiated Thyroid Cancer

Thyroid nodules occur fairly commonly, with a prevalence of 5% in women and 1% in men who live in iodine-sufficient regions. However, 7% to 15% of thyroid nodules are diagnosed as thyroid cancer.1 Primary thyroid cancers can be categorized by their cell of origin (endoderm vs neural crest c-cell).2 Endoderm-derived thyroid cancers can be further subdivided into differentiated thyroid cancer (DTC), poorly DTC, and anaplastic thyroid cancer.2

The most common form of thyroid cancer is DTC, which comprises over 90% of all thyroid cancers.1 DTC is subcategorized into papillary thyroid cancer (PTC) and follicular thyroid cancer (FTC).2 PTC accounts for 85% of all thyroid cancers and is genetically driven by BRAF V600E and RAS mutations.2 FTC occurs at a much lower frequency (5%) and is most commonly associated with RAS mutations and the PAX8-PPARy fusion gene.2

Incidence in the United States

The incidence rate of thyroid cancer is almost 3 times higher in women than in men.3 It was projected that in 2023, an estimated 43,720 new cases of thyroid cancer would be diagnosed in the United States.3 As diagnostic protocols have improved, estimations of thyroid cancer incidence rate have become more accurate.3

Epidemiology in the United States

The majority (94%) of thyroid cancers are diagnosed when tumors are either localized or restricted to regional spread.4 These localized and regional cases exhibit high rates of 5-year survival: 99.9% and 98%, respectively.4 Five-year survival rates decrease dramatically to just 53% among patients with distant metastases (3%).4

Risk Factors
 

Risk factors associated with thyroid cancer are largely intrinsic and include female sex, a history of goiter or thyroid nodules, a family history of thyroid cancer, radiation exposure at a young age, excess body weight, and certain genetic syndromes.3 People who test positive for a mutation in the RET gene can lower their risk of cancer development by having the thyroid gland surgically removed.3

Unmet Need
 

Although thyroid cancers are largely treatable, unmet needs remain among those with metastatic disease, particularly those with radioactive iodine (RAI)-refractory thyroid cancer, for which 5-year survival rates can be as low as 10%.2,4 Activation of the mitogen-activated protein kinase (MAPK) signaling pathway has been shown to inhibit sodium iodide symporter–based uptake of RAI.2 Thus, MAPK pathway inhibition is an area of active research.2

References: 1. Haugen et al. Thyroid. 2016;26:1-133. 2. Araque et al. Horm Metab Res. 2020;52:562-577. 3. American Cancer Society. Cancer Facts and Figures 2023. 4. National Cancer Institute. Surveillance, Epidemiology, and End Results Program. Cancer Stat Facts: Thyroid Cancer. https://seer.cancer.gov/statfacts/html/thyro.html. Accessed September 1, 2022.

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