Anaplastic thyroid cancer medical therapy
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]
Overview
Pharmacologic medical therapies for anaplastic thyroid cancer include radioactive iodine therapy and adjuvant radiotherapy.
Treatment
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.[1]
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.
Post-operative radiotherapy
The role of external beam radiotherapy (EBRT) in thyroid cancer remains controversial and there is no level I evidence to recommend its use in the setting of differentiated thyroid cancers such as papillary and follicular carcinomas. Anaplastic thyroid carcinomas, however, are histologically distinct from differentiated thyroid cancers and due to the highly aggressive nature of ATC aggressive postoperative radiation and chemotherapy are typically recommended.
The National Comprehensive Cancer Network Clinical Practice Guidelines currently recommend that postoperative radiation and chemotherapy be strongly considered. No published randomised controlled trials have examined the addition of external beam radiotherapy to standard treatment, namely surgery. Radioactive iodine is typically ineffective in the management of anaplastic thyroid cancer as it is not an iodine-avid cancer.[2]
Imbalances in age, sex, completeness of surgical excision, histological type and stage, between patients receiving and not receiving external beam radiotherapy, confound retrospective studies. Variability also exists between treatment and non-treatment groups in the use of radio-iodine and post-treatment thyroid stimulating hormone (TSH) suppression and treatment techniques between and within retrospective studies.
Some recent studies have indicated that external beam radiotherapy may be promising, though the number of patients studies has been small.[3]
Clinical trials for investigational treatments are often considered by healthcare professionals and patients as first-line treatment.
Adjuvant therapy
In the absence of extracervical or unresectable disease, surgical excision should be followed by adjuvant radiotherapy. In the 18–24% of patients whose tumour seems both confined to the neck and grossly resectable, complete surgical resection followed by adjuvant radiotherapy and chemotherapy could yield a 75–80% survival at 2 years.
There are a number of clinical trials for anaplastic thyroid carcinoma underway or being planned.[4]
References
- ↑ Haigh PI (2000). "Anaplastic thyroid carcinoma". Curr Treat Options Oncol. 1 (4): 353–7. doi:10.1007/s11864-000-0051-8. PMID 12057160.
- ↑ Ford D, Giridharan S, McConkey C, et al. (2003). "External beam radiotherapy in the management of differentiated thyroid cancer". Clin Oncol (R Coll Radiol). 15 (6): 337–41. doi:10.1016/S0936-6555(03)00162-6. PMID 14524487.
- ↑ Meadows KM, Amdur RJ, Morris CG, Villaret DB, Mazzaferri EL, Mendenhall WM (2006). "External beam radiotherapy for differentiated thyroid cancer". Am J Otolaryngol. 27 (1): 24–8. doi:10.1016/j.amjoto.2005.05.017. PMID 16360819.
- ↑ "American Thyroid Association - Thyroid Clinical Trials". Archived from the original on 12 December 2007. Retrieved 2007-12-21.