Thyroid Carcinoma Flashcards
How does a thyroid carcinoma present?
Thyroid cancer presents as a thyroid nodule. Thyroid nodules are frequent (4-50% depending on the diagnostic procedures and the patient’s age); however, thyroid cancer is rare (c. 5% of all thyroid nodules).
Solitary thyroid nodules can vary from soft to hard. Hard and fixed nodules are more suggestive of malignancy than soft mobile nodules. Thyroid carcinoma is usually non-tender to palpation.
Firm cervical masses are suggestive of regional lymph node metastases. Vocal cord paralysis implies involvement of the recurrent laryngeal nerve.
Red Flag Symptoms
A family history of thyroid cancer.
History of previous irradiation or exposure to high environmental radiation.
A child with a thyroid nodule.
Unexplained hoarseness or stridor associated with goitre.
A painless thyroid mass enlarging rapidly over a period of a few weeks.
Palpable cervical lymphadenopathy.
Insidious or persistent pain lasting for several weeks
Investigations for thyroid carcinoma
TFTs should be performed for any patient with a thyroid nodule. However, TFTs (most patients will be euthyroid) and thyroglobulin (Tg) measurement are of little help in the diagnosis of thyroid cancer.
Serum calcitonin is a reliable tool for the diagnosis of MTC (5-7% of all thyroid cancers).
Ultrasound:
Thyroid ultrasound is extremely sensitive for thyroid nodules and is used as a first-line diagnostic procedure for detecting and characterising nodular thyroid disease.[3]
Ultrasound features associated with malignancy include hypoechogenicity, microcalcifications, absence of peripheral halo, irregular borders, solid aspect, intranodular blood flow and shape (taller than wide).
Ultrasound should also be used to explore the neck carefully to assess the status of lymph node chains.
Fine-needle aspiration cytology (FNAC):
This should be performed in any thyroid nodule >1 cm and in those <1 cm if there is any clinical (history of head and neck irradiation, family history of thyroid cancer, suspicious features on palpation, presence of cervical lymphadenopathy) or ultrasound suspicion of malignancy.
The results of FNAC are very sensitive for the differential diagnosis of benign and malignant nodules, although limitations include inadequate samples and follicular neoplasia.
Radionuclide imaging: distinguishing functioning toxic nodules and thyroid metastases from follicular and papillary carcinomas is best with 123iodine uptake studies:
Normal iodine uptake is seen in ‘warm’ nodules. Lesions that take up excessive amounts of iodine are called ‘hot’ and those that do not take it up are called ‘cold’.
4% of hot nodules contain tumour, compared with 16% of cold nodules. This makes radionuclide imaging unreliable to exclude or confirm cancer. Low 123 iodine uptake in a single palpable nodule gives a risk of malignancy of 10-25%, falling to 1-3% if multiple nodules are demonstrated on the scan.
About half of papillary carcinomas and a smaller number of follicular carcinomas take up enough iodine in metastases to be detected.
Gallium 67 Ga is used in the diagnosis of thyroid lymphoma.
CT and MRI scan: CT scans and MRI scans are valuable to detect local and mediastinal spread and regional lymph node
How to manage a thyroid carcinoma?
Patients who have suspicious features (red flags - as above) should be referred urgently to a secondary care physician with expertise in the diagnosis and management of thyroid cancer, and seen within two weeks.
Any patient with a thyroid lump and associated stridor should be referred for same day review by a secondary care specialist, as this may be due to recurrent laryngeal nerve involvement secondary to a thyroid carcinoma.
Solitary thyroid nodules that are malignant, suspicious or indeterminate on FNA require operation.
Total thyroidectomy is recommended for patients with tumours greater than 4 cm in diameter, or tumours of any size in association with multifocal disease, bilateral disease, extra-thyroidal spread, familial disease, and those with clinically or radiologically involved nodes and/or distant metastases.
Because of the proximity of the right and left recurrent laryngeal nerves and risk of damage to the nerves, intraoperative nerve monitoring may be used during thyroid surgery, especially for re-operative surgery and operations on large thyroid glands.
Radioiodine remnant ablation and therapy for differentiated thyroid cancer:
Patients in the definite indications include tumour larger than 4 cm, or any tumour size with gross extra-thyroidal extension or distant metastases.
Patients with no indications include tumour 1 cm or smaller, classical papillary or follicular variant or follicular minimally invasive without angioinvasion and no invasion of thyroid capsule.
Adjuvant external beam radiotherapy for differentiated thyroid cancer should be considered for patients with a high risk of recurrence/progression with:
Gross evidence of local tumour invasion at surgery with significant macroscopic residual disease; or
Residual or recurrent tumour that fails to concentrate radioiodine, ie loco-regional disease where further surgery or radioiodine is ineffective or impractical.
Until recently, no truly effective treatment options have existed for patients with radioactive iodine-refractory differentiated thyroid cancer, which has a poor prognosis. A targeted multikinase inhibitor (sorafenib) has been shown to improve progression-free survival substantially. A number of other targeted agents are under investigation.[8]
Annual lifelong follow-up is recommended
