Primary and Central Hypothyroidism After Radiotherapy for Head-and-Neck Tumors

The Shrinking Thyroid: How Does Thyroid Size Change Following Radiation Therapy for Laryngeal Cancer?

“…[1][2][3][4][5][6][7][8][9][10][11][12] XRT causes microvascular and parenchymal damage to the gland, which results in decreased function several years after completing XRT. Eighty-five percent (52/61) of the patients included in this study demonstrated a measured decrease in the width of the thyroid gland on follow-up CT, with measurable changes occurring in several patients within the first quarter year following completion of XRT.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12] The percentage of patients developing hypothyroidism during the study period is likely exaggerated because lack of clinical data on thyroid function was an exclusion criterion for the study. A disproportionate number of euthyroid patients were probably excluded because it may be easier to document positive signs and symptoms of a disorder rather than negative signs and symptoms.…”

“…Hypothyroidism is documented in approximately 20%-67% of patients receiving XRT for Hodgkin or non-Hodgkin lymphoma and approximately 20%-31% of patients receiving XRT for head and neck cancers in the first 5 years after treatment. [1][2][3][4][5][6][7][8][9][10][11][12] Hypothyroidism typically occurs within 5 years after completing XRT. Morphologic changes to the thyroid gland after XRT, such as the development of solid or cystic masses, are well documented by sonography and histology.…”

An Update on Subclinical Hypopituitarism

“…There are studies that evaluated some isolated subclinical deficiencies. Subclinical thyroid-stimulating hormone (TSH) deficiency was reported in 20.3% of patients who were previously irradiated because of head and neck tumors [12] and in 38% of patients with type 2 diabetes [13], using the thyrotropic releasing hormone (TRH) test for diagnosis.…”

Endocrine Complications Following Radiotherapy and Chemotherapy for Nasopharyngeal Carcinoma

“…Primary hypothyroidism has been reported with fractionated radiotherapy with doses exceeding 25 Gy (Shalet et al, 1977). The probability of developing primary thyroid failure is significantly increased beyond 45 Gy (Bhandare et al, 2007). Chemotherapy has not been shown to influence the development of thyroid dysfunction following standard radiation therapy for head and neck cancers (Miller & Agrawal, 2009).…”