- Thyroid cancer
Thyroid cancer refers to any of four kinds of malignant
tumors of the thyroidgland: papillary, follicular, medullary or anaplastic. Papillary and follicular tumors are the most common. They grow slowly and may recur, but are generally not fatal in patients under 45 years of age. Medullary tumors have a good prognosis if restricted to the thyroid gland and a poorer prognosis if metastasisoccurs. Anaplastic tumors are fast-growing and respond poorly to therapy.
Thyroid nodules are diagnosed by ultrasound guided
fine needle aspiration(USG/FNA) or frequently by thyroidectomy(surgical removal and subsequent histological examination). As thyroid cancer can take up iodine, radioactive iodineis commonly used to treat thyroid carcinomas, followed by TSH suppression by thyroxinetherapy.
Most often the first symptom of thyroid cancer is a nodule in the thyroid region of the neck. However, many adults have small nodules in their thyroids. But typically under 5% of these nodules are found to be malignant. Sometimes the first sign is an enlarged lymph node. Later symptoms that can be present are pain in the anterior region of the neck and changes in voice.
Thyroid cancer is usually found in a
euthyroidpatient, but hyperthyroidismmay be a symptom of a large or metastatic well-differentiated tumor. Nodulesshould be of particular concern when they are found in children or those under the age of 20. The presentation of benign nodules at this age is less likely, and thus the potential for malignancy is far greater.
noduleis found during a physical examination, a referral to an endocrinologist, or a thyroidologistis the best approach. Most commonly an ultrasoundis performed to confirm the presence of a nodule, and assess the status of the whole gland. Measurement of thyroid stimulating hormoneand anti-thyroid antibodies will help decide if there is a functional thyroid disease such as Hashimoto's thyroiditispresent, a known cause of a benign nodular goiter. [cite journal |author=Bennedbaek FN, Perrild H, Hegedüs L |title=Diagnosis and treatment of the solitary thyroid nodule. Results of a European survey |journal=Clin. Endocrinol. (Oxf) |volume=50 |issue=3 |pages=357–63 |year=1999 |pmid=10435062 |doi=10.1046/j.1365-2265.1999.00663.x|url=http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=0300-0664&date=1999&volume=50&issue=3&spage=357]
Fine needle biopsy
One approach used to determine whether the nodule is malignant is the
fine needle biopsy(FNB) [cite journal |author=Ravetto C, Colombo L, Dottorini ME |title=Usefulness of fine-needle aspiration in the diagnosis of thyroid carcinoma: a retrospective study in 37,895 patients |journal=Cancer |volume=90 |issue=6 |pages=357–63 |year=2000 |pmid=11156519|doi=10.1002/1097-0142(20001225)90:6<357::AID-CNCR6>3.0.CO;2-4|url= ] , which some have described as the most cost-effective, sensitive and accurate test.Fact|date=December 2007 FNB or ultrasound-guided FNA usually yields sufficient thyroid cells to assess the risk of malignancy, although in some cases, the suspected nodule may need to be removed surgically for pathological examination.
Rarely, a biopsy is done using a large cutting needle, so that the a piece of nodule capsule can be obtained.
Blood or imaging tests may be done prior to or in lieu of a biopsy. The possibility of a nodule which secretes thyroid hormone (which is less likely to be cancer) or hypothyroidism is investigated by measuring
thyroid stimulating hormone(TSH), and the thyroid hormones thyroxine(T4) and triiodothyronine(T3).
Tests for serum thyroid autoantibodies are sometimes done as these may indicate
autoimmunethyroid disease (which can mimic nodular disease).
The blood assays may be accompanied by ultrasound imaging of the nodule to determine the position, size and texture, and to assess whether the nodule may be
cystic (fluid filled). Also suspicious findings in a nodule are hypoechoic,cite journal |author=Wong KT, Ahuja AT |title=Ultrasound of thyroid cancer |journal=Cancer Imaging |volume=5 |issue= |pages=157–66 |year=2005 |pmid=16361145 |doi=10.1102/1470-7330.2005.0110] irregular borders, microcalcifications, or very high levels of blood flow within the nodule. Less suspicious findings in benign nodules include, hyperechoic, comet tail artifacts from colloidClarifyme|date=September 2008, no blood flow in the nodule and a halo, or smooth border.
Some clinicians will also request
technetium(Tc) or radioactive iodine(I) imaging of the thyroidFact|date=September 2008. An 123I scan showing a hot nodule, accompanied by a lower than normal TSH, is strong evidence that the nodule is not cancerous.
Thyroid cancers can be classified according to their pathological characteristics.cite web |url=http://www.cancer.gov/cancertopics/pdq/treatment/thyroid/HealthProfessional/page2 |title=Thyroid Cancer Treatment - National Cancer Institute |accessdate=2007-12-22 |format= |work=] cite web |url=http://cancerweb.ncl.ac.uk/cancernet/101252.html#2_CELLULARCLASSIFICATION |title=Thyroid cancer |accessdate=2007-12-22 |format= |work=] The following variants can be distinguished (distribution over various subtypes may show regional variation):
Papillary thyroid cancer
Follicular thyroid cancer
Medullary thyroid cancer(up to 8%)cite journal |author=Schlumberger M, Carlomagno F, Baudin E, Bidart JM, Santoro M |title=New therapeutic approaches to treat medullary thyroid carcinoma |journal=Nat Clin Pract Endocrinol Metab |volume=4 |issue=1 |pages=22–32 |year=2008 |pmid=18084343 |doi=10.1038/ncpendmet0717]
Anaplastic thyroid cancer
Squamous cell carcinoma, sarcoma
The follicular and papillary types together can be classified as "differentiated thyroid cancer".cite journal |author=Nix P, Nicolaides A, Coatesworth AP |title=Thyroid cancer review 2: management of differentiated thyroid cancers |journal=Int. J. Clin. Pract. |volume=59 |issue=12 |pages=1459–63 |year=2005 |pmid=16351679 |doi=10.1111/j.1368-5031.2005.00672.x |url=http://www.medscape.com/viewarticle/518396] These types have a more favorable prognosis than the medullary and undifferentiated types.cite journal |author=Nix PA, Nicolaides A, Coatesworth AP |title=Thyroid cancer review 3: management of medullary and undifferentiated thyroid cancer |journal=Int. J. Clin. Pract. |volume=60 |issue=1 |pages=80–4 |year=2006 |pmid=16409432 |doi=10.1111/j.1742-1241.2005.00673.x |url=http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=1368-5031&date=2006&volume=60&issue=1&spage=80]
radioactive contamination(a cause of thyroid cancer)
* [http://www.thyroidtrials.org Thyroid Cancer Clinical Trials Page] of the American Thyroid Association
* [http://www.thyroidproblems.org/tumors.php Thyroid Tumors and Cancer - Thyroid Problems]
* [http://www.nucmedinfo.com/Pages/thyroid.html Nuclear Medicine Information =– Thyroid Diseases]
* [http://www.cancer.gov/cancertopics/types/thyroid Thyroid Cancer] - National Cancer Institute
* [http://www.thyca.org Thyroid Cancer Survivors' Association]
* [http://patients.uptodate.com/topic.asp?file=endocrin/11828 Diagnostic patient information]
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Look at other dictionaries:
thyroid cancer — Cancer that forms in the thyroid gland (an organ at the base of the throat that makes hormones that help control heart rate, blood pressure, body temperature, and weight). Four main types of thyroid cancer are papillary, follicular, medullary,… … English dictionary of cancer terms
thyroid cancer — any malignant tumour of the thyroid gland, of which there are four main types: papillary, follicular, medullary, and anaplastic. These have characteristic presentations and degrees of malignancy, ranging from the papillary tumours, which tend to… … The new mediacal dictionary
follicular thyroid cancer — Cancer that develops from cells in the follicular areas of the thyroid. One of the slow growing, highly treatable types of thyroid cancer … English dictionary of cancer terms
papillary thyroid cancer — Cancer that forms in follicular cells in the thyroid and grows in small finger like shapes. It grows slowly, is more common in women than in men, and often occurs before age 45. It is the most common type of thyroid cancer … English dictionary of cancer terms
anaplastic thyroid cancer — A rare, aggressive type of thyroid cancer in which the malignant (cancer) cells look very different from normal thyroid cells … English dictionary of cancer terms
familial medullary thyroid cancer — An inherited form of medullary thyroid cancer (cancer that forms in the cells of the thyroid that make the hormone calcitonin) … English dictionary of cancer terms
medullary thyroid cancer — Cancer that develops in C cells of the thyroid. The C cells make a hormone (calcitonin) that helps maintain a healthy level of calcium in the blood … English dictionary of cancer terms
Medullary thyroid cancer — Classification and external resources Micrograph of medullary thyroid carcinoma. H E stain. ICD 10 … Wikipedia
Follicular thyroid cancer — Classification and external resources Gross pathological section of a follicular thyroid adenoma (tumor at the bottom). ICD 10 C … Wikipedia
Papillary thyroid cancer — is the most common type of thyroid cancer in America, but not worldwide.Fact|date=April 2008 It occurs more frequently in women and presents in the 30 40 year age group. It is also the predominant cancer type in children with thyroid cancer, and… … Wikipedia