📈 The incidence of thyroid cancer — the most common endocrine malignancy — has risen sharply over the last 50 years. Despite this, most cases are detected early and have a good prognosis if not metastatic.

📖 About

🔎 Usually presents as a palpable thyroid nodule, but only 1 in 25 nodules are malignant.
👩 More common in women, though men tend to have a worse prognosis.
⏳ Peak incidence: 40–50 years of age.

🧬 Cancer Classifications

Broadly divided into differentiated (papillary, follicular, Hurthle cell) and undifferentiated (anaplastic), or by follicular vs non-follicular origin. Most patients present with localised disease. About 10% have distant metastases at diagnosis; cervical lymph node spread is common. FNA biopsy is the gold standard investigation for any thyroid nodule.

🦋 Thyroid Cancer — Detailed Comparison

Type	Pathology & Clinical Features 🔬	Genetics, Spread & Management 🎯
Papillary Thyroid Carcinoma (PTC) 📈	Most common (≈80–85%) Young–middle aged adults Orphan Annie nuclei 👁️ Nuclear grooves & inclusions Psammoma bodies 🌀 Often multifocal Painless thyroid nodule ± cervical lymphadenopathy	BRAF mutation common RET/PTC rearrangements Spreads via lymphatics → cervical nodes Excellent prognosis (>90–95% 10-year survival) Treatment: total thyroidectomy ± radioiodine ablation ☢️ Monitor with thyroglobulin levels
Follicular Thyroid Carcinoma (FTC) 🧬	≈10–15% of cases Encapsulated tumour Diagnosis requires capsular and/or vascular invasion Cannot distinguish from adenoma on FNA alone ⚠️ Usually solitary nodule	RAS mutation common PAX8-PPARγ rearrangement Spreads haematogenously → bone 🦴, lung 🫁 Good prognosis (slightly worse than PTC) Treatment: surgery ± radioiodine Monitor with thyroglobulin
Medullary Thyroid Carcinoma (MTC) 🧪	Arises from parafollicular C cells Produces calcitonin 📉 Amyloid stroma (calcitonin deposition) May cause flushing or diarrhoea Can be sporadic or familial	RET proto-oncogene mutation Associated with MEN2A / MEN2B 🧬 Check for pheochromocytoma before surgery ⚠️ Spreads early to lymph nodes No role for radioiodine ❌ Monitor with calcitonin & CEA
Anaplastic Thyroid Carcinoma 🚨	Rare (<2%) but highly aggressive Elderly patients 👵 Rapidly enlarging painful neck mass Dysphagia, hoarseness, airway compromise Undifferentiated histology	Often arises from pre-existing PTC/FTC p53 mutations common Locally invasive + distant metastases Very poor prognosis (median survival months) Treatment usually palliative (surgery/radiotherapy/chemotherapy)

🧪 Tumour Markers Comparison

Cancer Type	Tumour Marker	Radioiodine Sensitive?
Papillary	Thyroglobulin	Yes ✅
Follicular	Thyroglobulin	Yes ✅
Medullary	Calcitonin ± CEA	No ❌
Anaplastic	None reliable	No ❌

🧠 High-Yield Exam Summary:
Papillary = most common + lymphatic spread.
Follicular = blood spread + vascular invasion required.
Medullary = calcitonin + MEN2 (RET).
Anaplastic = aggressive elderly tumour with poor prognosis.

🔬 Investigations

🩸 Bloods: FBC, U&E, Ca, LFTs, TFTs.
📊 Thyroglobulin: sensitive tumour marker for differentiated cancers (papillary/follicular).
🔎 FNA biopsy: standard for any thyroid nodule.
☢️ Radioactive iodine uptake/whole body scans for staging and recurrence monitoring.

🛠️ General Management

✂️ Surgery: lobectomy, near-total or total thyroidectomy (depending on pathology).
☢️ Post-op radioactive iodine ablation for differentiated cancers.
💊 Long-term thyroxine replacement to maintain normal thyroid function and TSH suppression (reduces tumour stimulation).
🔎 Surveillance:
- Detectable thyroglobulin → recurrence or metastases (prompt whole-body I-131 scan).
- Neck US and clinical follow-up for local recurrence.
⚠️ Red flag features: elderly patient, hard fixed nodule, stridor, hoarseness (possible recurrent laryngeal nerve involvement).

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Thyroid Cancer