Anaplastic thyroid cancer
| Anaplastic thyroid cancer | |
|---|---|
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| Micrograph of anaplastic thyroid carcinoma. H&E stain. | |
| Classification and external resources | |
| Specialty | oncology |
| ICD-10 | C73 |
| ICD-9-CM | 193 |
| MedlinePlus | 000352 |
| eMedicine | med/2687 |
| MeSH | D013964 |
Anaplastic thyroid cancer (ATC) is a form of thyroid cancer which has a very poor prognosis due to its aggressive behavior and resistance to cancer treatments. Its anaplastic cells have poor differentiation, including dedifferentiation.
Anaplastic tumors have a high mitotic rate and lymphovascular invasion. They rapidly invade surrounding tissues (such as the trachea). The presence of regional lymphadenopathy in older patients in whom needle aspiration biopsy reveals characteristic vesicular appearance of the nuclei would support a diagnosis of anaplastic carcinoma.
It is always considered as stage IV.
The overall 5-year survival rate of anaplastic thyroid cancer has been given as 7% or 14%, although the latter has been criticized as being overestimated.
Treatment of anaplastic-type carcinoma is generally palliative in its intent for a disease that is rarely cured and almost always fatal, with worse prognosis associated with large tumours, distant metastases, acute obstructive symptoms, and leukocytosis. Death is attributable to upper airway obstruction and suffocation in half of patients, and to a combination of complications of local and distant disease, or therapy, or both in the remainder.
Anaplastic thyroid cancer is extremely aggressive; in most cases death occurs in less than 1 year as a result of aggressive local growth and compromise of vital structures in the neck. ATC in most series has a median survival of 4 to 5 months from the time of diagnosis, with rare long-term survivors.
Unlike its differentiated counterparts, anaplastic thyroid cancer is highly unlikely to be curable either by surgery or by any other treatment modality, and is in fact usually unresectable due to its high propensity for invading surrounding tissues.
Palliative treatment consists of radiation therapy usually combined with chemotherapy.
However, with today's technology, new drugs, such as fosbretabulin (a type of combretastatin), bortezomib and TNF-Related Apoptosis Induced Ligand (TRAIL), are being introduced and trialed in clinical labs and human clinical studies. Based on encouraging Phase I and II clinical trial results, with fosbretabulin, a type of drug that selectively destroys tumor blood vessels, a large, multi-national clinical trial is being undertaken to determine whether the drug can extend the survival of patients with ATC. Recent studies in Italy have shown positive results against ATC, but more tests outside the lab are needed to confirm this before it can be used in chemotherapy. There have been some case studies where patients with aggressive thyroid cancer have survived outside the mean expected survival time.
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