Thyroid Cancer

Thyroid cancer is a malignant tumour arising from the thyroid gland, with varying histological subtypes that affect prognosis and treatment.

Papillary thyroid carcinoma (PTC): the most common type, often associated with RET/PTC rearrangements and BRAF mutations.
Follicular thyroid carcinoma (FTC): linked to iodine deficiency, commonly spreads via haematogenous routes.
Medullary thyroid carcinoma (MTC): arises from parafollicular C cells and is associated with MEN2 syndrome.
Anaplastic thyroid carcinoma: a rare, aggressive form with poor prognosis.
Lymphoma: primary thyroid lymphoma can occur, often associated with Hashimoto’s thyroiditis.

Thyroid cancer originates from follicular or parafollicular thyroid cells, leading to uncontrolled proliferation.
Papillary and follicular carcinomas tend to spread via lymphatic and haematogenous routes, respectively.
Medullary carcinoma produces calcitonin, which can cause systemic symptoms like diarrhoea and flushing.
Anaplastic carcinoma is highly invasive, often presenting with rapid growth and airway obstruction.

Female sex (higher incidence in women).
Radiation exposure (e.g., childhood radiation therapy).
Family history of thyroid cancer or genetic syndromes (e.g., MEN2, Cowden syndrome).
Chronic thyroid inflammation (e.g., Hashimoto’s thyroiditis).
Iodine deficiency (associated with follicular carcinoma).

Neck mass: painless thyroid nodule or swelling.
Compressive symptoms: dysphagia, hoarseness, dyspnoea (due to tracheal compression).
Lymphadenopathy: palpable cervical lymph nodes in metastatic disease.
Systemic symptoms: unexplained weight loss, fatigue (late-stage disease).

Thyroid function tests: typically normal, but may show hypothyroidism in Hashimoto’s-related lymphoma.
Ultrasound: assesses nodule characteristics (e.g., irregular margins, microcalcifications).
Fine-needle aspiration (FNA) biopsy: first-line for cytological evaluation.
Serum calcitonin: elevated in medullary thyroid carcinoma.
CT/MRI: for assessing local invasion or metastases.
Radioiodine scan: used in differentiated thyroid cancers to assess uptake and metastatic spread.

Thyroidectomy: total or partial thyroidectomy depending on tumour type and size.
Lymph node dissection: indicated for lymph node involvement.

Used post-surgery for differentiated thyroid cancers (papillary, follicular) to ablate residual thyroid tissue.

Tyrosine kinase inhibitors (TKIs): used in advanced or metastatic disease (e.g., lenvatinib, sorafenib).
Chemotherapy: reserved for anaplastic thyroid cancer due to poor response to other treatments.