- RET/PTC rearrangement: 20% papillary thyroid cancer - RET: medullary thyroid cancer

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1 Thyroid Cancer UpToDate: Introduction: Risk Factors: Biology: Symptoms: Diagnosis: 1. Lenvina is the first line therapy with powerful durable response and superior PFS in pts with RAI-refractory disease. 2. Vandetanib (Caprelsa): FDA approved for late stage (metastatic) medullary thyroid cancer in adults who are ineligible for surgery. - Cancers of thyroid gland. - Asian descent most commonly affacted. - Incidence is rising in recent years. - Median age of onset: 35 and 65 yrs. 1) Radiation exposure during childhood (<10yrs): increased risk for papillary thyroid cancer. 2) Familial syndromes: Gardner syndrome, familial adenomatous polyposis, Cowden syndrome, Carney complex. - RET/PTC rearrangement: 20% papillary thyroid cancer - RET: medullary thyroid cancer - Thyroid nodule A. Thyroid nodule evaluation: 1) Thyroid nodal with low TSH Radioiodine imaging (RAI) two possibilities: - If nodule hot unlikely to be cancer treat thyrotoxicosis as indicated. - If nodule cold or warm FNA. 2) Thyroid nodule with normal or elevated TSH FNA B. US threshold for FNA: Threshhold for FNA Solid nodule * w/ suspecious US features > 1.0 cm * w/o suspecious US features > 1.5 cm Mixed cystic-solid nodule * w/ suspecious US features cm * w/ suspecious US features > 2.0 cm Spongiform nodule >2.0cm Simple cyst Not indicated. Suspecious cervical lymph node FNA node +/- FNA thyroid nodules Pathology: A. Classification: 1) Well-differentiated from follicular cells (90%) - Papillary - Follicular - mixed Page 1 of 6

2 - Hurthle cell carcinoma: a follicular carcinoma variant, also known as Oxyphil cell carcinoma, worse prognosis, less iodine-avid than papillary or follicular carcinoma. 2) Poorly differentiated from follicular cells (1-2%) - Anaplastic carcinoma: giant cell variant, very poor prognosis, always stage IV at diagnosis, median OS 3-4 mos. DDx: large cell lymphoma of thyroid 3) Derived from parafollicular cells - Medullary: calcitonin-producing B. Staging: T1: <2cm, within thyroid T1a: <1 cm T1b: 1-2 cm T2: 2-4 cm, within thyroid T3: >4cm, within thyroid; or any tumor with minimal extrathyroid extension T4: Invade adjacent structures T4a: invade adjacent structure including recurrent laryngeal nerve T4b: invade prevertebral fascia or carotid artery ** All anaplastic cancers are T4 tumor: T4a intrathyroidal anaplastic ca, T4b with gross extrathyroid extension. N1: regional lymph nodes N1a, N1b M1:distant metastasis A. Papillary or Follicular (differentiated): Under 45 yrs - Stage I: any T, any N, M0 - Stage II: any T, any N, M1 45 yrs or older - Stage I: T1, N0, M0 - Stage II: T2, N0, M0 - Stage III: T3, N0, M0 T1-3, N1a, M0 - Stage IVA: T4a, N0-1a, M0 T1-4a, N1b, M0 IVB: T4b, any N, M0 IVC: any T, any N, M1 B. Medullary Carcinoma (all age group) Stage I: T1, N0, M0 Stage II: T2-3, N0, M0 Stage III: T1-3, N1a, M0 Page 2 of 6

3 Stage IVA: T4a, N0-1a, M0 T1-4a, N1b, M0 IVB: T4b, any N, M0 IVC: anyt, anyn, M0 C. Anaplastic Carcinoma: All considered stage IV Stage IVA: T4a, any N, M0 IVB: T4b, any N, M0 IVC: anyt, anyn, M0 Prognosis: Tx Principle: Most favorable except anaplastic carcinoma A. Well Differentiated Thyroid Cancer (Paplillary and Follicular): 1) Surgery: - Indication for total thyroidectomy (any present): T >4.0 cm, RT history, extrathyroidal extension, known distant metastasis, cervical lymph node positive, bilateral disease, high-risk histology (tall cell variants, columinar, or poorly differentiated). * For follicular invasive cancer total thyroidectomy only, NO lobectomy (inadequate, not recommended) - Indication for unilateral lobectomy and isthmusectomy (all present) Age 15-45y, T<4..0cm, confined to one lobe, NO high-risk histology, NO RT history, NO distant metastasis, No extrathyroid extension, NO cervical lymph node. - Lymph node dissection: * If neck lymph node palpable or biopsy positive for metastasis perform central and lateral neck dissection * If node negative for metastasis NO neck dissection needed or consider prophylactic central neck dissection. 2) Post-Op Evaluation and Management: - Order radioiodine scan only if RAI therapy is considered. 2.1 If no gross residual disease in neck: "TSH + Tg (thyroglobulin) + anti-tg Ab + total body radioiodine scan with thyroid hormone withdrawl or rtsh stimulation" between 2-12 wks post-op; - Observe if Tg <1ng/ml, negative anti-tg Ab, and RAI scan. - RAI therapy indicated if: * positive RAI uptake RAI therapy ( mCi), and add EBRT if primary is T4 tumor with extrathyroid extension and age >45y. * stimulated Tg >10ng/ml, even with negative RAI uptake RAI therapy 2.2 If gross residual disease present in neck: - If resectable re-resect (surgery) - If unresectable "TSH + Tg (thyroglobulin) + anti-tg Ab + RAI scan with thyroid hormone withdrawl or rtsh stimulation" * if positive RAI uptake RAI therapy. Page 3 of 6

4 * if no RAI uptake consider EBRT if positive biopsy. 2.3 Summary for Radioiodine (RAI) therapy: - All pts with high-risk features (any one): male>40yrs, female >50yrs, incomplete resection, capsular invasion, distant metastasis, tumor > 4 cm. - If primary tumor 1-4 cm, RAI therapy only for selected high-risk pts (lymph node metastasis, vascular invasion, aggressive variant) - For primary tumor <1cm without high-risk features NO RAI. 3) TSH suppression(by levothyroxine): indicated all patients following above treatment. - Below 0.1 mu/l for all high-risk patients or patients with structural residual disease. - Between 0.1 and 0.5 mu/l for low-risk patients or patients with no structural residual disease even if Tg positive. 4) Follow-up: - H& P, TSH, Tg, anti-tg Ab, q 6-12 months, then annually if disease-free * TSH-stimulated Tg measurement in patients previously treated with RAI therapy. * TSH-stimulated RAI scan in high-risk patients with history of RAI avid metastasis, abnormal Tg, anti-tg Ab, or US) - If stimulated Tg >2.5 ng/ml with negative RAI scan CT, or PET-CT, or US 5) Recurrent or Metastatic Disease: 5.1 First line therapy: - Biochemical recurrence of stimulated Tg 1-10ng/ml without structural evidence of tumor (i.e. negative RAI scan or other images) suppress TSH with levothyroxine. - Locoregional recurrence surgery if resectable (preferred) or RAI therapy if positive RAI uptake, or EBRT if negative RAI uptake. - If stimulated Tg >10ng/ml RAI therapy post-treatment RAI scan. 5.2 Metastatic thyroid cancer refractory to RAI: - Chemotherapy: Doxorubicin-based combination (doxorubicin/cisplatin) or single agent (Doxorubicin) - Lenvina: newly approved for RAI-refractory thyroid cancers. B. Medullary Thyroid Cancer (MTC): 1) Work-up after biopsy disgnosis - basal calcitonin, CEA; calcium - Pheochromocytoma screening: urine metanephrine/catecholamine, CT chest/abd/pelvis to r/o adrenal mass. - Screen for RET mutations. (codon 10, 11, 13-16) - Neck US, or CT chest, mediastinum or MRI if N1 disease or calcitonin >400pg/ml 2) MEN: - MEN1 (3P): Pituitary adenoma, Pancreatic iselet tumor, Parathyroid adenoma - MEN2 A: Thyroid medullary ca, Pheochromocytoma, Parathyroid adenoma B: Thyroid medullary ca, Pheochromocytoma, Neuroma, Manfanoid body Page 4 of 6

5 3) Treatment: 3.1 Surgery: - If T> 1cm, total thyroidectomy plus bilateral central neck dissection. Add postop RT if incomplete resection or gross extrathyroidal extension - If T<1cm, total thyroidectomy, consider neck dissection - If family members with positive RET mutations prophylactic total thyoidectomy: 3.2 RAI has NO role in medullary thyroid cancer. 3.3 Rx levothroxine to normalize TSH level (does not have to suppress TSH level below normal value). 3.4 Follow-up calcitonin and/or CEA - If negative for calcitonin/cea negative, observe. - If positive for calcitonin/cea, neck imaging and CT or MRI C/A. * if negative, oberve and follow-up, q6-12 months with calcitonin/cea. Imaging as clinically indicated. * if positive, tx recurrent dz 4) Metastatic or recurrent disease: often indolent - Local recurrent surgical resection +/- EBRT, or Vandetanib if unresectable or symptomatic or progressive - Symptomatic distant metastasis palliative resection, EBRT for focal symptoms, or Vandetanib, or DTIC-based chemo. Bisphosphonate or denosumab for bone metastasis - Asymtomatic distant metastasis often indolent observe C. Anaplastic Thyroid Cancer: All stage IV, rapidly progressing - Surgery is usually NOT an option. Sometimes, it can be used to control local symptoms and patient often require tracheostomy. - Standard Tx: RT +/- radiosensitizers (doxorubicin +/- cisplatin) palliate local symptoms - RAI has NO role. Chemo alone has NO role. Follow-Up: A. Papillary or follicular thyroid cancer post thyroidectomy +/- RAI 1) H& P, TSH, thyroglobulin (Tg), anti-thyroglobulin (Tg) antibody, q 6-12 months, then annually if disease-free. - A rise in Tg antibodies with or without a corresponding rise in serum Tg may predict disease recurrence. 2) Imaging: - Neck US - In high-risk patients with persistent positive anti-tg antibodies, consider CT chest/neck or PET-CT). B. Medullary thyroid cancer follow-up - Calcitonin/CEA Pharmacology: A. RAI therapy: mainstay treatment B. Lenvima: C. Vandetanib (Caprelsa): inhibit RET-tyrosine kinase activity Page 5 of 6

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