Thyroid Cancer

Related Subjects: |Thyrotoxicosis and Hyperthyroidism |Thyroid Storm - Thyrotoxic crisis |Graves Disease (Thyrotoxicosis) |Amiodarone and Thyroid disease |Thyroid Surgery (Thyroidectomy) |Hypothyroidism |Hashimoto's thyroiditis |DeQuervain's thyroiditis |Subacute Thyroiditis |Thyroid nodule |Congenital Hypothyroidism |Thyroid Function Tests and antibodies |Post partum thyroiditis |Sick Euthyroid Syndrome |Thyroid Exam (OSCE) |Thyroid Gland anatomy and Physiology |Thyroid Cancer

The incidence of thyroid cancer, the most common endocrine malignancy, has increased dramatically in the last fifty years.

About

• Usually presents as a palpable thyroid abnormality
• However only 1 in 25 palpable nodules are cancerous
• It is commoner in women but men have a worse prognosis

Cancer Classifications

• Cancers can be regarded as differentiated or not. Also divided into those from follicular cell origin or not. Thyroid Cancer affects generally those aged 40-50. Most have localised disease at diagnosis and only 10% have metastases. Prognosis is good if not distant metastases. Most have cervical nodes involved. FNA is the standard diagnostic procedure when a thyroid nodule is found
• Papillary Thyroid Carcinoma 85-90%: Commonest. Young people. Good prognosis. 50% on biopsy have laminated calcified lesions called Psammoma bodies. Risks Exposure to radiation - local lymph node spread is typical.
• Follicular Thyroid Carcinoma < 10%: Females. Bloodborne spread to the brain, bone, lung and liver. Age 40-50. Risks Exposure to radiation. hemithyroidectomy to distinguish between follicular adenoma and follicular carcinoma on histopathological examination. Complete thyroidectomy and postoperative radioiodine ablation where carcinoma is confirmed. This way total thyroidectomy is not carried out unnecessarily.
• Hurthle Cell Carcinoma: unusual and rare. a variant of follicular carcinoma. Hurthle cells have abundant eosinophilic granular cytoplasm as a result of the accumulation of altered mitochondria. Most likely to spread in the differentiated cancers to lungs, bone and brain. Unilateral hemithyroidectomy is performed for non-invasive disease and total thyroidectomy for invasive disease.
• Undifferentiated Thyroid Cancer: Anaplastic Thyroid Carcinoma: Aggressive. Seen in elderly. Usually inoperable and very poor prognosis
• Cancer of Parafollicular (C) Cells : Medullary Thyroid Carcinoma 3%:Elevated serum calcitonin and carcinoembryonic antigen (CEA). Consider. Multiple endocrine neoplasia types 2, Amyloidosis. Treat surgically with radiotherapy

Investigations

• FBC, U&E, Ca, LFTs, TFTs, Thyroglobulin is a very sensitive tumour marker
• FNA of the thyroid is the standard diagnostic procedure when a thyroid nodule is found
• Oral Radioactive Iodine concentrates in the thyroid

General Management

• Thyroid lobectomy or near-total thyroidectomy
• Treatment is with Total Thyroidectomy and radioactive Iodine
• Long term thyroxine is given to maintain T3 and T4 but more importantly to suppress TSH as some differentiated cancers may be TSH dependant
• Detectable Thyroglobulin suggests recurrence or metastases and a total body Iodine ¹³¹ scan is needed which helps localise the disease.
• Elderly patients, hard nodule - Stridor hoarseness due to Recurrent laryngeal nerve compression.