📋 Key Information Summary
- Thyroid cancer is the most common endocrine malignancy; age-standardised incidence in Australia is approximately 14 per 100,000 and rising, partly due to increased detection of small papillary tumours.
- Differentiated thyroid cancer (DTC) — papillary (~80%) and follicular (~10%) — carries an excellent prognosis (5-year survival >95% for localised disease) and is managed primarily with surgery ± radioiodine (I-131).
- Medullary thyroid cancer (MTC) arises from parafollicular C-cells; ~25% are hereditary (RET proto-oncogene mutations). Calcitonin and CEA are essential tumour markers.
- Anaplastic thyroid cancer (ATC) is rare (<2%) but highly aggressive with median survival 3–6 months; requires urgent multidisciplinary team (MDT) discussion and molecular profiling.
- Total or near-total thyroidectomy is the standard surgical approach for tumours >4 cm, bilateral/multifocal disease, or extrathyroidal extension; lobectomy is appropriate for low-risk unifocal tumours ≤4 cm.
- Radioiodine (I-131) ablation is indicated post-operatively for high-risk and intermediate-risk DTC; low-risk patients may be observed without ablation (per 2015 ATA risk stratification).
- TSH suppression with levothyroxine targets TSH 0.1–0.5 mIU/L for intermediate risk and <0.1 mIU/L for high risk; low-risk patients aim for low-normal TSH.
- Tyrosine kinase inhibitors (lenvatinib, sorafenib) are PBS-authority options for progressive radioactive iodine-refractory differentiated thyroid cancer and advanced medullary thyroid cancer (vandetanib, cabozantinib).
- Molecular testing (BRAF V600E, RAS, TERT promoter, RET/PTC, NTRK fusions) is increasingly important for risk stratification, diagnosis of indeterminate cytology, and selection of targeted therapies.
- ATSI Australians have lower incidence but often present at later stage; culturally safe pathways and remote-access MDT support are essential.
- All patients require lifelong surveillance: thyroglobulin (Tg) monitoring post-thyroidectomy, neck ultrasound, and whole-body I-131 scan when indicated.
- All thyroid cancer management should be discussed at an endocrine / head-and-neck MDT meeting per Australian Cancer Care Standards.
🎧 Audio Brief
Introduction & Australian Epidemiology
Thyroid cancer encompasses a heterogeneous group of malignancies arising from thyroid follicular epithelial cells (papillary, follicular, anaplastic) and parafollicular C-cells (medullary). It is the most common endocrine malignancy worldwide and has shown a persistent increase in incidence over recent decades.
Australian Incidence & Trends
- Age-standardised incidence rate (ASR): ~14.0 per 100,000 (2022 AIHW data); approximately 4,500 new diagnoses per year in Australia.
- Female-to-male ratio approximately 3:1; peak incidence in women aged 40–59 years.
- Papillary thyroid cancer (PTC) accounts for ~80% of all thyroid cancers; follicular thyroid cancer (FTC) ~10%; medullary thyroid cancer (MTC) ~4%; anaplastic thyroid cancer (ATC) ~1–2%.
- Five-year relative survival for all thyroid cancers in Australia is approximately 96%, reflecting the favourable prognosis of DTC subtypes.
- Rising incidence attributed partly to incidental detection of small papillary microcarcinomas on imaging (ultrasound, CT, PET) — "overdiagnosis" debate ongoing.
- Thyroid cancer is the 9th most common cancer in Australian women and the 19th most common in men.
Risk Factors
- Ionising radiation exposure (especially childhood head/neck irradiation).
- Family history of thyroid cancer or hereditary syndromes (MEN2A/2B, FAP, Cowden syndrome, familial DTC).
- Iodine deficiency (linked to follicular subtype); Australia is generally iodine-replete but remote/regional areas may have borderline intake.
- Obesity — emerging epidemiological association with PTC.
- Hashimoto's thyroiditis — associated with PTC (controversial).
Australian Cancer Care Standard: All patients with a new diagnosis of thyroid cancer should be referred for multidisciplinary team (MDT) discussion, ideally within 2 weeks of histological diagnosis, per Cancer Australia and the National Cancer Control Indicators.
Classification & Epidemiology
Thyroid cancers are classified by cell of origin, histological subtype, and molecular profile. The 2022 WHO Classification of Endocrine and Neuroendocrine Tumours is the current standard.
| Subtype | Origin | Frequency | Prognosis | Key Molecular Features |
|---|---|---|---|---|
| Papillary (PTC) | Follicular epithelium | ~80% | Excellent (10-yr OS >95%) | BRAF V600E (~45%), RAS (~10%), RET/PTC rearrangements, TERT promoter co-mutations (worse prognosis) |
| Follicular (FTC) | Follicular epithelium | ~10% | Good (10-yr OS ~85%) | RAS (~40%), PIK3CA, PAX8-PPARγ rearrangement |
| Hürthle cell | Oncocytic follicular | ~3% | Moderate | Mitochondrial DNA mutations, complex genomic profiles |
| Medullary (MTC) | Parafollicular C-cells | ~4% | Moderate (10-yr OS ~75%) | RET proto-oncogene (germline in 25%, somatic in ~65%) |
| Anaplastic (ATC) | Dedifferentiated follicular | ~1–2% | Very poor (median OS 3–6 months) | BRAF V600E, TP53, TERT promoter — often co-occurring |
TNM Staging (AJCC/UICC 8th Edition)
Staging differs for DTC, MTC, and ATC. Age ≥55 years is a critical threshold in DTC staging, upstaging many patients.
| DTC Stage (age <55 yr) | Criteria |
|---|---|
| I | Any T, any N, M0 |
| II | Any T, any N, M1 |
| DTC Stage (age ≥55 yr) | Criteria |
|---|---|
| I | T1, N0/Nx, M0 (with ETE ≤T2 if N0) |
| II | T1–2 N1 M0, or T3a–3b any N M0 |
| IVA | T4a any N M0, or T1–3 N1a M0 |
| IVB | T4b any N M0, or any T N1b M0 |
| IVC | Any T, any N, M1 |
Papillary & Follicular (Differentiated) Thyroid Cancer
Differentiated thyroid cancer (DTC) encompasses papillary thyroid cancer (PTC) and follicular thyroid cancer (FTC). These tumours retain iodine avidity and TSH-responsive growth, which underpin the treatment paradigm of surgery + radioiodine + TSH suppression.
Papillary Thyroid Cancer
- Most common subtype (~80%); female predominance (3:1).
- Often multifocal within the thyroid; spreads via lymphatics to cervical lymph nodes (central and lateral compartments).
- Classic papillary, follicular variant (most common variant), tall cell, hobnail, and diffuse sclerosing subtypes — tall cell and hobnail variants have more aggressive behaviour.
- BRAF V600E mutation present in ~45% — associated with extrathyroidal extension, lymph node metastasis, and radioactive iodine (RAI) refractoriness when co-mutated with TERT promoter.
Follicular Thyroid Cancer
- ~10% of thyroid cancers; more common in iodine-deficient regions; higher prevalence in elderly patients.
- Haematogenous spread (lungs, bones) more common than lymphatic spread.
- Diagnosis requires capsular and/or vascular invasion on histology (distinguishes FTC from follicular adenoma).
- Hürthle cell (oncocytic) carcinoma — previously classified under FTC, now a separate entity in WHO 2022; generally less iodine-avid.
Multidisciplinary MDT: All DTC patients should be managed by an MDT including endocrinologist, endocrine/head-and-neck surgeon, nuclear medicine physician, radiation oncologist, pathologist, and radiologist. Referral to a high-volume surgeon improves outcomes — target >25 thyroidectomies per year per surgeon.
Medullary & Anaplastic Thyroid Cancer
Medullary Thyroid Cancer (MTC)
- Arises from parafollicular C-cells; produces calcitonin and CEA — essential tumour markers for diagnosis and surveillance.
- ~75% sporadic; ~25% hereditary (MEN2A, MEN2B, familial MTC) via germline RET proto-oncogene mutations.
- RET mutations: highest risk — M918T (MEN2B), high risk — C634R (MEN2A), moderate risk — other codon 634, 609, 611, 618, 620 mutations.
- Does NOT take up iodine — radioiodine therapy is not effective.
- Pre-operative workup must include calcitonin, CEA, plasma/urine metanephrines (to exclude phaeochromocytoma before thyroid surgery), serum calcium/PTH (hyperparathyroidism in MEN2A).
Critical safety alert: All patients with confirmed or suspected MTC must have phaeochromocytoma excluded (plasma free metanephrines) BEFORE thyroid surgery. Undiagnosed phaeochromocytoma during anaesthesia can cause fatal hypertensive crisis.
Anaplastic Thyroid Cancer (ATC)
- Rare (~1–2%) but the most aggressive thyroid malignancy; median survival 3–6 months.
- Most patients present with rapidly enlarging neck mass, dysphagia, dyspnoea, and hoarseness — symptoms of local invasion.
- Often arises from pre-existing DTC through dedifferentiation; molecular drivers include BRAF V600E, TP53, TERT promoter mutations.
- Emerging targeted therapies: dabrafenib + trametinib for BRAF V600E-mutant ATC (PBS available via authority); pembrolizumab may be considered.
- Requires urgent MDT discussion, supportive care goals-of-care planning, and molecular profiling of tumour tissue.
Dabrafenib + Trametinib
Tafinlar® + Mekinist® · BRAF/MEK inhibitor combination
Indication
BRAF V600E-mutant anaplastic thyroid cancer
Adult dose
Dabrafenib 150 mg PO BD + Trametinib 2 mg PO OD, continuously
Key side effects
Pyrexia, rash, fatigue, nausea, haemorrhage risk
PBS status
Authority Required
Clinical Presentation & Diagnostic Criteria
Typical Presentations
- Solitary thyroid nodule: Most common presentation — usually painless, firm, palpable; majority are benign (90–95% of nodules).
- Incidental finding: Increasingly detected on ultrasound, CT, PET-CT performed for other indications.
- Cervical lymphadenopathy: May be the presenting feature of PTC, especially in younger patients.
- Rapidly enlarging neck mass: Suggestive of ATC or aggressive DTC variant.
- Symptoms of local invasion: Hoarseness (recurrent laryngeal nerve), dysphagia (oesophageal compression), dyspnoea (tracheal compression), Horner's syndrome (sympathetic chain).
- Diarrhoea / flushing: May indicate metastatic MTC (calcitonin-mediated secretory diarrhoea).
- Bone pain / pathological fracture: Bone metastases, particularly FTC.
Diagnostic Workup of a Thyroid Nodule
- Thyroid function tests: TSH, free T4, free T3. Suppressed TSH may suggest a benign autonomous nodule; do not exclude malignancy.
- Neck ultrasound: First-line imaging; assess nodule size, composition, echogenicity, margins, calcifications, and vascularity. Use ACR TI-RADS or EU-TIRADS classification.
- Fine-needle aspiration biopsy (FNAB): Gold standard for cytological diagnosis; indicated for nodules meeting size threshold on TI-RADS score (e.g., TI-RADS 4–5 ≥10 mm; TI-RADS 3 ≥25 mm). Performed under ultrasound guidance.
- Bethesda classification of FNAB: Six categories (I–VI) from non-diagnostic to malignant; guides management.
- Molecular testing (Afirma, ThyroSeq): Consider for Bethesda III (AUS/FLUS) or Bethesda IV (follicular neoplasm) cytology to reduce unnecessary diagnostic surgery.
| Bethesda Category | Risk of Malignancy | Recommended Action |
|---|---|---|
| I — Non-diagnostic | 5–10% | Repeat FNAB (ultrasound-guided) or molecular testing |
| II — Benign | 0–3% | Surveillance ultrasound at 12–24 months |
| III — AUS/FLUS | 10–30% | Repeat FNAB, molecular testing, or diagnostic lobectomy |
| IV — Follicular neoplasm | 25–40% | Diagnostic lobectomy or molecular testing |
| V — Suspicious for malignancy | 50–75% | Total thyroidectomy or lobectomy (based on clinical factors) |
| VI — Malignant | 97–99% | Total thyroidectomy (most cases) |
Investigations
Essential
Neck Ultrasound
First-line imaging for thyroid nodule assessment and cervical lymph node survey. ACR TI-RADS classification. MBS Item 55060.
Essential
Ultrasound-Guided Fine-Needle Aspiration Biopsy (FNAB)
Cytological diagnosis using Bethesda system. Performed by endocrinologist, radiologist, or surgeon. MBS Item 30217.
Essential
Thyroid Function Tests
TSH, free T4, free T3. Baseline assessment and post-treatment monitoring. MBS Item 66716.
Essential
Calcitonin & CEA
If MTC suspected or confirmed. Pre-operative and surveillance levels. MBS Item 66819.
Essential
Plasma Free Metanephrines
Mandatory before thyroidectomy in MTC to exclude phaeochromocytoma. MBS Item 66822.
Available
Diagnostic CT Neck/Chest (with contrast)
For locally advanced disease, retrosternal extension, lung metastases. Does NOT contain iodine contrast if radioiodine planned within 2–3 months. MBS Item 56809.
Available
Whole-Body Diagnostic I-131 or I-123 Scan
Post-thyroidectomy (prior to ablation or during surveillance). Assess iodine avidity and detect distant metastases. Nuclear medicine.
Available
Thyroglobulin (Tg) & Anti-Thyroglobulin Antibodies
Key tumour marker post-total thyroidectomy. MBS Item 66781.
Available
Molecular Profiling (BRAF, RAS, TERT, RET, NTRK)
Available at major pathology laboratories; clinically relevant for indeterminate FNAB, MTC (RET), and targeted therapy selection in advanced disease.
Specialist
PET-CT (F-18 FDG)
For RAIR-DTC (radioactive iodine-refractory) disease, ATC staging, or elevated Tg with negative iodine scan. Limited PBS MBS access; often self-funded or research-partnered.
Specialist
RET Germline Genetic Testing
For all confirmed MTC patients and first-degree relatives. Performed by genetics service. Implications for prophylactic thyroidectomy in MEN2 carriers.
Risk Stratification
The 2015 American Thyroid Association (ATA) risk stratification system, adapted for Australian practice, guides the extent of initial therapy and intensity of follow-up.
Low Risk
ATA Low Risk
- No local or distant metastases
- Complete macroscopic resection
- No vascular invasion
- No aggressive histology (tall cell, hobnail, columnar)
- cN0 or ≤5 pathologic micrometastases (<0.2 cm)
Post-op: Consider no RAI ablation; surveillance Tg + US
Intermediate Risk
ATA Intermediate Risk
- Microscopic extrathyroidal extension
- Vascular invasion
- Aggressive histology variants
- BRAF V600E mutation (if other risk factors present)
- cN1 or >5 pathologic lymph node metastases
- Multifocal papillary microcarcinoma with ETE and BRAF+
Post-op: RAI ablation (30–100 mCi); TSH target 0.1–0.5 mIU/L
High Risk
ATA High Risk
- Gross extrathyroidal extension (T4)
- Incomplete tumour resection (R1 or R2)
- Distant metastases (M1)
- Post-operative Tg suggestive of distant disease
- pN1 with lymph nodes >3 cm
Post-op: High-activity RAI (100–200 mCi); TSH <0.1 mIU/L; consider EBRT for local disease
Management: Surgery, Radioiodine & TSH Suppression
Surgery
Surgery is the primary curative treatment for thyroid cancer. The extent of thyroidectomy and lymph node dissection is guided by tumour size, multifocality, extrathyroidal extension, and nodal disease.
| Surgical Procedure | Indications | Key Considerations |
|---|---|---|
| Thyroid lobectomy | Unifocal DTC ≤4 cm, no ETE, N0, low-risk histology; benign diagnostic uncertainty | Avoids lifelong thyroxine if contralateral lobe normal; requires completion thyroidectomy if high-risk features found on final histology |
| Total / near-total thyroidectomy | Tumour >4 cm, bilateral/multifocal, ETE, N1, M1, prior head/neck radiation, familial DTC | Allows RAI ablation and Tg surveillance; higher hypoparathyroidism and recurrent laryngeal nerve injury rates at low-volume centres |
| Central compartment dissection (VI) | Clinically positive central nodes (cN1a); prophylactic in DTC >4 cm or T3–T4 | Increased transient hypoparathyroidism risk |
| Lateral neck dissection (II–V) | Clinically positive lateral nodes (cN1b) — therapeutic only | Not recommended prophylactically; perform selective (not radical) dissection |
Surgeon volume matters: Australian data show that surgeons performing >25 thyroidectomies per year have significantly lower complication rates. Patients should be referred to high-volume endocrine or head-and-neck surgical units where available.
Radioactive Iodine (RAI) Therapy — I-131
RAI ablation exploits the iodine-uptake mechanism of differentiated thyroid cancer cells. It is used post-operatively to ablate residual thyroid tissue and treat microscopic or macroscopic residual/metastatic disease.
Indications for RAI Ablation
- High-risk DTC: Always indicated — high-activity I-131 (3.7–7.4 GBq / 100–200 mCi).
- Intermediate-risk DTC: Generally indicated — low-to-intermediate activity (1.1–3.7 GBq / 30–100 mCi).
- Low-risk DTC: May be omitted (ATA 2015 trend towards less aggressive ablation); individualised decision.
- MTC and ATC: NOT indicated — these tumours do not concentrate iodine.
Preparation for RAI
- TSH stimulation: TSH must be >30 mIU/L. Achieved by either thyroid hormone withdrawal (THW — 3–4 weeks of thyroxine cessation) or recombinant human TSH (rhTSH, Thyrogen® — preferred for quality of life).
- Low-iodine diet for 1–2 weeks prior.
- Check urine iodine if iodine contamination suspected.
- Avoid iodinated contrast for ≥2 months before RAI.
Recombinant Human TSH (rhTSH)
Thyrogen® · Thyrotropin alfa
Route / dose
0.9 mg IM × 2 doses (24 hours apart), followed by I-131 on day 3
Advantage
Avoids hypothyroid symptoms of thyroid hormone withdrawal
PBS status
Authority Required
Side Effects of RAI
- Sialadenitis / xerostomia (most common — advise sour lollies/citrus post-RAI).
- Taste disturbance, nausea (acute).
- Transient radiation thyroiditis.
- Rare: second primary malignancies (leukaemia, salivary gland tumours) — risk increases with cumulative dose.
- Gonadal toxicity — counsel regarding fertility preservation before high-dose RAI.
TSH Suppression Therapy
Levothyroxine is used to suppress TSH below the normal range, as TSH stimulates DTC cell growth via the TSH receptor.
Levothyroxine Sodium
Oroxine® / Eutroxsig® · T4 replacement / TSH suppression
Adult dose (suppression)
1.5–2.0 µg/kg/day PO OD, 30 min before breakfast; titrate to target TSH
TSH targets
High risk: <0.1 mIU/L · Intermediate: 0.1–0.5 mIU/L · Low risk: low-normal (0.5–2.0 mIU/L)
Renal adjustment
No dose adjustment; monitor TSH closely in CKD
Key interactions
Calcium, iron, PPIs reduce absorption — separate by ≥4 hours
PBS status
✔ PBS General Benefit
Atrial fibrillation & osteoporosis risk: Aggressive TSH suppression (<0.1 mIU/L) increases the risk of atrial fibrillation (especially in elderly >65 years) and osteoporosis (especially postmenopausal women). Use the lowest TSH-suppressive dose compatible with the clinical risk of recurrence. Monitor bone density (DEXA) and cardiac rhythm.
External Beam Radiation Therapy (EBRT)
- Consider for locally advanced DTC with gross residual disease, incomplete resection, or ATC.
- Not a routine part of DTC management; reserved for RAI-refractory locoregional disease.
- ATC: EBRT (intensity-modulated) often combined with radiosensitising chemotherapy (doxorubicin, paclitaxel) and/or targeted therapy.
Targeted Systemic Therapies for Advanced / Refractory Disease
Lenvatinib
Lenvima® · Multi-kinase inhibitor
Indication
Locally recurrent or metastatic, progressive RAIR-DTC
Adult dose
24 mg PO OD (reduce dose for toxicity: 20 mg → 14 mg → 10 mg)
Key side effects
Hypertension, proteinuria, diarrhoea, fatigue, hand-foot syndrome, QT prolongation
Monitoring
BP weekly for 6 months, then 2-weekly; urine protein; LFTs; ECG; TFTs (may increase TSH)
PBS status
Authority Required
Sorafenib
Nexavar® · Multi-kinase inhibitor
Indication
Progressive RAIR-DTC
Adult dose
400 mg PO BD
Key side effects
Hand-foot syndrome, diarrhoea, hypertension, rash, fatigue
PBS status
Authority Required
Vandetanib
Caprelsa® · Multi-kinase inhibitor (RET, VEGFR, EGFR)
Indication
Unresectable, locally advanced or metastatic MTC
Adult dose
300 mg PO OD
Key side effects
QT prolongation (mandatory ECG monitoring), diarrhoea, rash, hypertension
PBS status
Authority Required
Cabozantinib
Cometriq® · Multi-kinase inhibitor (RET, MET, VEGFR2)
Indication
Progressive metastatic MTC
Adult dose
140 mg PO OD (reduce to 100 mg or 60 mg for toxicity)
Key side effects
Diarrhoea, hand-foot syndrome, weight loss, hypertension, perforation/fistula risk
PBS status
Authority Required
Selpercatinib
Retevmo® · Selective RET inhibitor
Indication
RET-mutant MTC or RET fusion-positive thyroid cancer (advanced/progressive)
Adult dose
160 mg PO BD
Key side effects
Hepatotoxicity (monitor LFTs), hypertension, QT prolongation, dry mouth
PBS status
PBS Restricted Benefit
Monitoring & Surveillance
Long-term follow-up is essential for all thyroid cancer patients. The intensity and tools depend on initial ATA risk stratification and response-to-therapy assessment.
Differentiated Thyroid Cancer — Post-Thyroidectomy Surveillance
| Time Point | Low Risk | Intermediate Risk | High Risk |
|---|---|---|---|
| 6–12 months | Neck US, TSH, Tg (±TgAb) | Neck US, TSH, Tg, diagnostic WBS if Tg detectable | Neck US, TSH, Tg, diagnostic WBS |
| Annually (years 1–5) | TSH, Tg; neck US if clinically indicated | TSH, Tg, neck US annually | TSH, Tg, neck US, ± diagnostic WBS, CT if indicated |
| After 5 years | Extend to 2–3 yearly TSH/Tg | Annual or 2-yearly TSH/Tg + US | Annual lifelong (may extend interval if excellent response) |
Response-to-Therapy Assessment
At 6–18 months post-initial therapy, patients are re-stratified based on biochemical and structural evidence:
- Excellent response: Stimulated Tg <1 ng/mL (or <0.2 ng/mL if using high-sensitivity assay), negative imaging → continue surveillance.
- Biochemical incomplete: Stimulated Tg ≥10 ng/mL or rising TgAb, but no structural disease → ongoing monitoring; consider repeat imaging.
- Structural incomplete: Persistent or new structural disease on imaging → further surgery, RAI, EBRT, or systemic therapy as indicated.
- Indeterminate response: Non-specific findings (e.g., mildly elevated Tg, equivocal US) → close follow-up.
Medullary Thyroid Cancer — Surveillance
- Calcitonin and CEA every 3–6 months (if elevated post-operatively, doubling time is prognostic).
- Cross-sectional imaging (CT chest/abdomen) annually or with rising markers.
- Calcitonin doubling time <2 years suggests aggressive disease — consider systemic therapy referral.
General Monitoring Parameters
- Thyroid function tests (TSH, free T4) every 6–12 weeks during dose titration, then every 6–12 months.
- Calcium, phosphate, PTH post-total thyroidectomy (monitor for hypoparathyroidism).
- Vitamin D levels — particularly in patients on TSH suppression (bone health).
- DEXA scan — postmenopausal women and men >50 years on long-term TSH suppression.
Special Populations
Pregnancy
Diagnosis in pregnancy
FNAB is safe in pregnancy. Surgery can be deferred to second trimester or post-partum for DTC (which is typically indolent). Avoid RAI in pregnancy — contraindicated, causes fetal hypothyroidism.
Levothyroxine in pregnancy
TSH target in DTC pregnancy: 0.1–1.0 mIU/L in first trimester, then 0.3–2.0 mIU/L. Increase LT4 dose by ~25–30% as soon as pregnancy confirmed. Monitor TSH every 4 weeks in first trimester.
Post-partum
RAI and surgery can be planned post-partum. Breastfeeding must be discontinued if I-131 administered (typically cease 6–8 weeks prior or permanently).
Paediatric Thyroid Cancer
Epidemiology
Rare in children <10 years; incidence rises in adolescence. More commonly presents with lymph node metastases and lung metastases than adults, but paradoxically has better prognosis.
Surgery
Total thyroidectomy recommended for most paediatric DTC (due to high multifocality rates). Performed at a paediatric surgical centre with endocrine surgery expertise.
RAI
Generally indicated post-operatively. Dose adjusted for body weight (37–74 MBq/kg). Thyrogen® is TGA-approved for paediatric use. Long-term follow-up essential (second malignancy risk).
MEN2 / prophylactic thyroidectomy
RET mutation carriers (MEN2B with M918T): prophylactic total thyroidectomy in first 6 months of life. MEN2A with C634R: surgery by age 5. Follow international guidelines (ATA/ATA Pediatric).
Elderly Patients
Risk profile
Higher proportion of FTC, Hürthle cell, and ATC in older patients. More aggressive presentation with vascular invasion and distant metastases.
TSH suppression
Balance recurrence risk against AF and osteoporosis risk. In low-risk elderly DTC, TSH 0.5–2.0 mIU/L may be appropriate. Avoid prolonged TSH <0.1 in patients >65 years unless high-risk disease.
Surgical risk
Assess cardiopulmonary fitness for general anaesthesia. Consider limited surgery (lobectomy) if surgical risk is prohibitive. RFA or active surveillance for small incidental papillary microcarcinomas in frail patients.
Renal Impairment
Levothyroxine
No formal dose adjustment required, but TSH may be less reliable in CKD. Monitor free T4 alongside TSH. Drug absorption may be altered in dialysis patients.
RAI clearance
I-131 is renally cleared. Patients with eGFR <30 mL/min require dose reduction and extended radiation safety precautions post-therapy.
Hepatic Impairment
Lenvatinib / Sorafenib
Hepatotoxic — contraindicated or dose-reduced in Child-Pugh B/C. Monitor LFTs at baseline, then every 2 weeks for 2 months, then monthly.
Levothyroxine
No hepatic dose adjustment, but hypoalbuminaemia may alter free hormone levels.
Immunocompromised Patients
Immunotherapy in ATC
Pembrolizumab may be considered in ATC; immunocompromised patients (transplant, HIV with low CD4) may have reduced efficacy and increased immune-related adverse events.
Infection risk
Post-RAI neutropenia is rare but possible with high doses. Monitor FBC after high-dose I-131 therapy.
Aboriginal and Torres Strait Islander Health Considerations
Aboriginal and Torres Strait Islander Health
📚 References
- 1. Haugen BR, Alexander EK, Bible KC, et al. 2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer. Thyroid. 2016;26(1):1–133.
- 2. Wells SA Jr, Asa SL, Dralle H, et al. Revised American Thyroid Association guidelines for the management of medullary thyroid carcinoma. Thyroid. 2015;25(6):567–610.
- 3. Smallridge RC, Ain KB, Asa SL, et al. American Thyroid Association guidelines for management of patients with anaplastic thyroid cancer. Thyroid. 2012;22(11):1104–1139.
- 4. Amin MB, Edge SB, Greene FL, et al. (Eds). AJCC Cancer Staging Manual. 8th ed. New York: Springer; 2017.
- 5. Baloch ZW, Asa SL