Thyroid cancer

Papillary, follicular, or oncocytic (previously known as Hürthle cell)

• For patients treated with total thyroidectomy and adjuvant radioactive iodine (RAI) therapy, a whole-body RAI scan at 6 to 12 months after adjuvant RAI therapy is suggested for patients at high or intermediate risk of persistent disease.[1]Haugen BR, Alexander EK, Bible KC, et al; American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer. 2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer. Thyroid. 2016 Jan;26(1):1-133. https://www.liebertpub.com/doi/10.1089/thy.2015.0020 http://www.ncbi.nlm.nih.gov/pubmed/26462967?tool=bestpractice.com Recombinant human thyroid-stimulating hormone (TSH) is used to increase the TSH levels, while the patient continues to be on thyroid hormone replacement. The scan detects residual thyroid tissue in the neck and also metastases.[Figure caption and citation for the preceding image starts]: Increased uptake of radioiodine in both pulmonary fields and the mediastinum due to miliary lung metastasis from papillary thyroid carcinomaGkountouvas A, Chatjimarkou F, Thomas D, et al. Miliary lung metastasis due to papillary thyroid carcinoma. BMJ Case Reports. 2009; doi:10.1136/bcr.06.2008.0322 [Citation ends].

• During follow-up the best investigations are thyroglobulin, thyroglobulin antibody, and clinical examination. Thyroglobulin panel is an important investigation if the patient has undergone total thyroidectomy and radioiodine ablation. Any rise in thyroglobulin or thyroglobulin antibody is suggestive of recurrent thyroid carcinoma, most of which is recurrence in either the central compartment of the neck or the lateral neck.[29]Gharib H, Papini E, Garber JR, et al. American Association of Clinical Endocrinologists, American College of Endocrinology, and Associazione Medici Endocrinologi medical guidelines for clinical practice for the diagnosis and management of thyroid nodules - 2016 update. Endocr Pract. 2016 May;22(5):622-39. https://www.endocrinepractice.org/article/S1530-891X(20)42954-4/fulltext http://www.ncbi.nlm.nih.gov/pubmed/27167915?tool=bestpractice.com

• Although there is no definitive cut-off for thyroglobulin, >2 micrograms/L (2 nanograms/mL) is considered worrisome and >10 micrograms/L (10 nanograms/mL) suggests recurrent thyroid carcinoma. Thyroglobulin panel (including antibodies) may be performed twice yearly for the first 5 years and subsequently once yearly (if normal).

• Ultrasound is done at baseline, and then annually combined with more frequent clinical examinations. Ultrasound may detect recurrent disease in the thyroid bed, the paratracheal area, or the lateral neck.

• An elevated thyroglobulin or rising thyroglobulin antibodies are generally investigated with ultrasound and whole-body RAI scan. Recurrent disease or metastasis is ablated with I-131. Surgery may also be used for accessible disease.

• Positron emission tomography/computed tomography (PET/CT) can be used to look for recurrent disease in patients with raised thyroglobulin and negative radioactive iodine scan.[95]Royal College of Physicians (UK). Evidence-based indications for the use of PET-CT in the UK 2016. May 2016 [internet publication]. https://www.rcplondon.ac.uk/projects/outputs/evidence-based-indications-use-pet-ct-uk-2016

Medullary

• Medullary cancer is monitored with serum calcitonin every 3 months for 2 years, followed by every 6 months for 3 years. If levels are undetectable they can then be followed annually. If serum calcitonin is elevated, ultrasound and CT of the neck/chest are indicated. If both are negative, PET scan may detect lesions missed by CT.[95]Royal College of Physicians (UK). Evidence-based indications for the use of PET-CT in the UK 2016. May 2016 [internet publication]. https://www.rcplondon.ac.uk/projects/outputs/evidence-based-indications-use-pet-ct-uk-2016

Hypocalcaemia

• Incidence of permanent hypocalcaemia due to parathyroid injury is extremely low. If post-operative hypocalcaemia persists for >3 weeks, it is more likely to be permanent. Treatment is with oral calcium and vitamin D.