5th April 2024

Thyroid cancer

Background

Thyroid cancers can be broadly divided into those arising from thyroid follicular epithelium (papillary, follicular and anaplastic) or calcitonin producing C cells (medullary cancer). Thyroid hormone levels are very rarely deranged with thyroid cancers and hence are not associated with symptoms of hypo or hyperthyroidism. Instead, they secrete thyroglobulin which acts as a tumour marker post treatment. Certain cancers metastasise to the thyroid gland. These include renal, colon, breast, and melanoma.

Thyroid cancer subtypes

• Papillary is the most common subtype of thyroid cancer, occurring mainly in young people, with female preponderance. Presentation is with a nodule and associated with lymph node metastasis. Histologically, there is an encapsulated papillae consisting of one or two layers of tumour cells surrounding a well-defined fibrovascular core.  Management involves surgery and radioiodine. Papillary cancer has a good prognosis and can be monitored by measurement of thyroglobulin levels
• Follicular cancer also presents as a thyroid nodule and is associated with capsular and vascular invasion. It affects middle aged people and is more common in women. The management is similar to papillary cancer
• Hürthle/Oxyphil cell thyroid cancer is usually classified as a type of follicular thyroid cancer but it is distinct in that it grows more aggressively. Tumours can be benign or malignant
• Anaplastic cancer mainly affects the elderly and can present as a mass effect secondary to local invasion. This subtype carries a poor prognosis
• Medullary thyroid cancer is associated with raised calcitonin levels. It may be sporadic or inherited as a genetic condition called MEN2. The increased risk of malignancy is a consequence of the RET oncogene
• Lymphoma of the thyroid gland is rare and associated with Hashimoto’s. The majority of the cases are B cell lymphoma

References

Thyroid lymphoma. Last updated 8ᵗʰ September 2021. Available at: https://www.ncbi.nlm.nih.gov/books/NBK544282