--- title: "Thyroid Cancer" description: "ENT notes on Thyroid Cancer - Classification, Risk factors, Staging, Investigations and Treatment." source: "The ENT Resident" author: "Dr. Mausumi Das" canonical_url: "https://www.theentresident.com/ent-notes-lectures/thyroid-cancer-causes-symptoms-staging" categories: ["Thyroid"] video: "https://www.youtube.com/watch?v=0m14Iq_gzYg" image: "https://media.theentresident.com/og-images/thyroid-cancer-causes-symptoms-staging.png" --- # Thyroid Cancer ENT notes on Thyroid Cancer - Classification, Risk factors, Staging, Investigations and Treatment. Watch the full video lecture on YouTube: https://www.youtube.com/watch?v=0m14Iq_gzYg ## 🦋 Thyroid Cancer – Classification, Risk Factors, Staging, Investigations & Treatment **Thyroid cancer** accounts for about **1% of all cancers in the body** and has a higher incidence in females. - **Sex ratio:** Female : Male = **3 : 1** - **Peak incidence:** 3rd–4th decades of life --- ### 📑 Classification of Thyroid Tumors **1. WHO Classification (comprehensive list):** - Follicular adenoma - Hyalinizing trabecular tumor - Other encapsulated follicular pattern thyroid tumors - Papillary thyroid carcinoma - Follicular thyroid carcinoma - Hürthle cell tumor - Poorly differentiated thyroid carcinoma - Anaplastic carcinoma - Squamous cell carcinoma - Medullary thyroid carcinoma - Mixed medullary + follicular carcinoma - Mucoepidermoid carcinoma (± with eosinophilia) - Mucinous carcinoma - Ectopic thymoma - Spindle epithelial tumor - Intrathyroid thymic carcinoma - Paraganglioma - Mesenchymal stromal tumors - Hematolymphoid tumors - Germ cell tumors - Secondary tumors **2. Simplified Classification:** - **Benign:** Follicular adenoma, Hürthle cell adenoma, microfollicular adenoma, embryonal adenoma - **Malignant:** a. **Primary:** - From **follicular epithelium**: - Papillary carcinoma - Follicular carcinoma - Anaplastic carcinoma - From **parafollicular C cells**: Medullary carcinoma - From **lymphoid tissue**: Lymphoma b. **Secondary:** - **Metastasis** (kidney, lung, colon, breast) - **Direct spread** (larynx, post-cricoid carcinoma) >What is the most common Benign thyroid tumor? >What is the most common malignant thyroid tumor? --- ### ⚠️ Risk Factors for Thyroid Cancer - **Age:** 30–40 years most common; >65 yrs → risk of anaplastic carcinoma - **Sex:** Females > males - **Family history** Gardner syndrome, Cowden syndrome - **Genetic:** - Medullary carcinoma → MEN2A, MEN2B - Papillary carcinoma → Gardner & Cowden syndromes - **Radiation exposure:** Strongest risk factor - **Other risks:** Endemic goiter, Graves’ disease, inborn errors of metabolism >What are the features of MEN2A and MEN2B syndrome? >What are the mutations associated with Papillary, Follicular and Medullary Thyroid Cancer? --- ### 🩺 Clinical Features of Thyroid Cancer - **Thyroid nodule:** - Usually **painless** - Hard, fixed - Solitary or multiple >What are red flag signs in Thyroid nodule that point towards malignancy? - **Other features:** - **Cervical lymphadenopathy** - **Pressure symptoms:** - Hoarseness (RLN involvement) - Dysphagia (esophagus compression) - Dyspnea (tracheal compression) - **Horner’s syndrome:** Miosis, ptosis, anhidrosis (sympathetic chain compression) - **Constitutional:** Weight loss, fatigue, fever, night sweats - Rapidly enlarging pre-existing goiter --- ### 🧾 TNM Staging of Thyroid Cancer **T Staging:** - **T1:** ≤2 cm, confined to thyroid - T1a: ≤1 cm - T1b: >1–2 cm - **T2:** >2–4 cm, confined to thyroid - **T3:** - T3a: >4 cm confined to thyroid - T3b: any size with extrathyroid extension to strap muscles - **T4:** Gross extrathyroid extension - T4a: Invades subcutaneous tissue, larynx, trachea, esophagus, RLN - T4b: Invades prevertebral fascia, mediastinal vessels, carotid artery **N Staging:** - **Nx:** Cannot assess - **N0:** No Lymph Node involvement - **N1a:** Level VI (pretracheal, paratracheal, prelaryngeal, superior mediastinal) - **N1b:** Unilateral, bilateral, or contralateral cervical Lymph Nodes (levels I–V) or retropharyngeal Lymph Nodes **M Staging:** - **M0:** No distant metastasis - **M1:** Distant metastasis present **Residual Tumor Status:** - **R0:** No residual tumor - **R1:** Microscopic residual - **R2:** Macroscopic residual --- ### 🎯 Stage Grouping **Medullary Thyroid Carcinoma:** - Stage I: T1a/b, N0 - Stage II: T2/T3, N0 - Stage III: T1–T3, N1a - Stage IVA: T1–T3, N1b or T4a - Stage IVB: T4b - Stage IVC: Any T, Any N, M1 **Papillary & Follicular Carcinoma:** **< 55 years:** - Stage I: Any T, Any N, M0 - Stage II: Any T, Any N, M1 **≥ 55 years:** - Stage I: T1–T2, N0 - Stage II: T1–T3, N1 or T3 N0 - Stage III: T4a - Stage IVA: T4b - Stage IVB: Any M1 --- ### 🧪 Investigations in Thyroid Cancer - **Blood tests:** - ESR ↑ - Thyroid function tests (T3, T4, TSH) - Anti-thyroid antibodies - Serum thyroglobulin - Serum calcitonin >Which is the biochemical marker of medullary thyroid cancer? - **Imaging:** - **Ultrasound (first-line)** >What are the suspicious features in ultrasound suggesting thyroid malignancy? - **FNAC (gold standard):** Except follicular carcinoma (can’t differentiate adenoma vs carcinoma) → use Bethesda system - **CT/MRI:** Extent, cartilage invasion, retrosternal spread, lymph node assessment - **CT Abdomen:** If lymphoma suspected or MEN syndrome evaluation - **Thyroid scintigraphy:** - Tc-99m scan → Cold nodule (20% risk of malignancy) vs Hot nodule (unlikely malignant) - MIBG scan → MEN syndrome (pheochromocytoma + medullary carcinoma) - Gallium citrate → Thyroid lymphoma - I-131 scan → Post-surgical ablation - **Special tests:** - Serum calcitonin + CEA (medullary carcinoma) - RET mutation analysis (MEN syndrome) - Core biopsy (anaplastic carcinoma) - Laryngoscopy (pre-op baseline RLN function) --- ### 💊 Treatment of Thyroid Cancer **1. Surgery (Primary Treatment):** - **Thyroidectomy types:** - Hemithyroidectomy (1 lobe + isthmus) - Subtotal thyroidectomy (>50% both lobes + isthmus) - Near-total thyroidectomy (1 complete lobe + isthmus + >90% opposite lobe) - Total thyroidectomy (both lobes + isthmus) - Completion thyroidectomy (convert lesser operation to total) - **Neck Dissection:** If nodal involvement present **2. Radioiodine Ablation (I-131):** - For residual tissue/microscopic disease >What is the indication of Radioiodine ablation in Thyroid malignancy? **3. External Beam Radiotherapy (EBRT):** - Unresectable tumors - Residual disease not responsive to I-131 - Palliative (bone/brain mets) **4. Thyroid Hormone Suppression Therapy:** - Levothyroxine to suppress TSH - High risk → TSH < 0.1 mIU/L - Low risk → TSH 0.1–0.5 mIU/L **5. Chemotherapy:** - Limited role --- ## About This Note This free ENT note on Thyroid Cancer was written by Dr. Mausumi Das and is paired with a corresponding video lecture. 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