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Thyroid Cancer

Thyroid Carcinoma

Thyroid cancer is a rare malignancy that affects the thyroid gland.


Presentation

Thyroid cancer is generally noticed as a painless, distinct, solitary nodule in the thyroid region (lower) of the throat externally. Solitary nodules have a much higher chance of turning out to be malignant in older patients beyond 60 years of age or in patients younger than 30 years.

Patients may complain of change in voice or increase in hoarseness. They may also complain of dysphagia due to digestive tract involvement. Growth of nodule is a sign of malignancy.

Thyroid nodules when present in males have higher chances of being malignant. Enlargement of lymph nodes situated in the neck region can also be a sign of malignancy. Patients with family history of thyroid carcinoma must be checked thoroughly.

Axillary Lymphadenopathy
  • He presented to our cancer clinic at the Oncology Centre -Mansoura University with recurrent mass at the right lower parotid region, left cervical lymphadenopathy and left axillary lymphadenopathy.[ncbi.nlm.nih.gov]
Thyroid Nodule
  • Thyroid nodules are present in up to 50% of the adult population, as determined by ultrasonography, and less than 15% of thyroid nodules are malignant ( 1 - 6 ).[kjronline.org]
  • Abstract Differentiation of benign and malignant thyroid nodules is crucial for clinical management.[ncbi.nlm.nih.gov]
  • Siobhan Pittock, Thyroid Nodules in Children, Thyroid Nodules, 10.1007/978-3-319-59474-3_14, (207-231), (2017). Zubair W. Baloch, David S. Cooper, Hossein Gharib and Erik K.[dx.doi.org]
Goiter
  • Chest goiter removal removes goiters (enlarged thyroid) that extend into the chest. Removal of cancer that has spread to other areas of the neck (neck dissections) may be necessary when cancers spread to lymph nodes or organs in the neck.[dukehealth.org]
  • Competitive allele-specific Taqman PCR was performed in 147 samples of thyroid tissue DNA obtained from patients histologically diagnosed with papillary thyroid cancer (PTC), colloid goiters, and follicular adenomas.[ncbi.nlm.nih.gov]
  • Substernal goiter: analysis of 80 patients from Massachusetts General Hospital. Am J Surg. 1985;149(2):283-287. PubMed Google Scholar Crossref 11. Yamaguchi S, Fujii T, Yajima R, et al.[doi.org]
  • These symptoms may be caused by thyroid cancer; other thyroid problems, such as a goiter; or a condition not related to the thyroid, such as an infection.[cancer.net]
  • Therefore, patients should ask their relatives for a family history of papillary thyroid cancer, goiter Goiter - enlarged thyroid, colon/rectal tumors, or breast cancer.[endocrinediseases.org]
Thyroid Lump
  • But when faced with the C-word you probably can’t rationally take in that most thyroid lumps are benign (not cancer).[thyroiduk.org.uk]
  • About 19 out of 20 thyroid lumps are benign. In some cases the biopsy will show that there is thyroid cancer present. Unfortunately sometimes the biopsy does not give a definitive answer.[btf-thyroid.org]
  • Symptoms vary depending on the type of thyroid cancer, but may include: Cough Difficulty swallowing Enlargement of the thyroid gland Hoarseness or changing voice Neck swelling Thyroid lump (nodule) Your health care provider will perform a physical exam[nlm.nih.gov]
  • The tests available to your physician for evaluation of the thyroid lump include, but are not limited to, the following: Fine-needle aspiration biopsy – this is usually done first and, if positive, significantly reduces the need for more elaborate and[thyroidawareness.com]
Malignant Pleural Effusion
  • She received lenvatinib (24 mg once a day) at only two doses during two weeks due to pleurodesis with talc for malignant pleural effusion. Eventually, she developed peritonitis due to the perforation and died of sepsis.[ncbi.nlm.nih.gov]
Neck Swelling
  • Symptoms vary depending on the type of thyroid cancer, but may include: Cough Difficulty swallowing Enlargement of the thyroid gland Hoarseness or changing voice Neck swelling Thyroid lump (nodule) Your health care provider will perform a physical exam[nlm.nih.gov]
  • Talk to your healthcare provider right away if you have any of the following signs and/or symptoms: A lump that you can feel on your neck, sometimes with no other symptoms Neck swelling Voice changes, including increasing hoarseness Trouble breathing[labtestsonline.org]

Workup

The ultimate goal of workup is to differentiate the nodule into malignant or benign. Following are the means of tests used to determine this:

  • First and foremost is a thorough examination of the suspected patients which includes: Careful examination of head and neck along with thyroid gland and soft tissue in cervical region.
  • Indirect laryngoscopy

Hard cervical masses suggest metastases of regional lymph nodes and paralysis of vocal fold suggests recurrent laryngeal nerve involvement.

Laboratory tests

  • FNAC (fine needle aspiration biopsy): This is an important diagnostic test in evaluating thyroid nodules [5]. On basis of the results of this test, we can know if the nodule is benign or malignant. In around 50% of the cases, the test gives definitive diagnosis but in patients whose findings are non-diagnostic, we can repeat the biopsy or tissue diagnosis can be done by undergoing surgery,
  • Serum TSH levels: A sensitive TSH assay helps in evaluating solitary thyroid nodules for e.g. low serum TSH levels are suggestive of autonomously functioning nodule.
  • Serum calcitonin levels: High levels of serum calcitonin indicates the presence of medullary thyroid carcinoma [6].
  • Polymerase chain reaction (PCR) assay for germline mutations in the RET proto-oncogene helps in diagnosing familial medullary thyroid carcinoma [7].

Imaging studies

  • Ultrasonography (USG): Neck USG is commonly used in evaluating thyroid diseases, but it is not very useful in differentiating the malignant and benign nodules. Many low risk thyroid cancer cases were diagnosed due to widespread usage of USG [8] [9].
  • Thyroid radioiodine imaging: It helps in determining operational status of a nodule but it does not rule out cancer.
  • CT scan or MRI scan: Helps in evaluating the neck region completely for any mass or metastatic lymph nodes.

Treatment

Following are the different ways of treating thyroid cancer:

  1. Surgery: In most of the cases, the entire thyroid gland is removed (thyroidectomy) along with the surrounding enlarged lymph nodes. In few cases, if the cancer is very small, only the affected lobe is removed.
  2. Radioactive iodine therapy: After 4-6 weeks of surgery, this therapy is started in which the patient is given a pill of radioactive iodine to destroy any thyroid cancer tissue if present even after surgery.
  3. Thyroid hormone therapy: Once the gland is removed, you need to supplement the body with thyroid hormone and hence one has to take this pill for lifetime after the operation. It replaces the need of thyroid hormone thyroxin and prevents the TSH levels from increasing which can stimulate any remaining cancer cells to grow.
  4. External radiation therapy: This procedure is used if the patient cannot undergo surgery or if the cancer continues to grow after radioactive iodine therapy.
  5. Chemotherapy: This modality of treatment uses potent drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing.
  6. Targeted drug therapy: It is therapy in which drugs are used such that they identify and attack the cancer cells without harming the normal cells. Sorafenib and sunitinib are the latest drugs being used to treat thyroid cancers [10].

Prognosis

Papillary and follicular thyroid cancers are the most common types of the thyroid cancer. Both these carcinomas have very good prognosis i.e. they are most curable ones. These carcinomas have 97% cure rate in younger patients when treated properly.

Medullary thyroid carcinoma is not seen much but has poor prognosis. This cancer spreads faster to the surrounding lymph nodes and hence requires more aggressive treatment.

Anaplastic thyroid cancer is rarely seen and has the worst prognosis. It is diagnosed after the spread has taken place and patient is almost incurable. It is rare to survive this cancer as many a times even the surgery cannot remove the tumor entirely.

Etiology

The risk of developing thyroid cancer increases with benign thyroid conditions like thyroiditis or goitre. Exposure to radiation in childhood can increase the risk of developing thyroid malignancies, mainly papillary thyroid carcinoma. Exposure to radiations during medical procedures may also lead to thyroid cancer.

Inherited genetic mutations are responsible for a small number of medullary thyroid carcinomas. Low dietary intake of trace element iodine has higher chances of developing follicular or anaplastic carcinoma.

Epidemiology

In 2010, thyroid cancer resulted in 36,000 deaths around the world as compared to 24,000 in 1990 [1]. Yearly, 1% new cases of thyroid cancer are diagnosed. The incidence of thyroid cancer is 3 folds more in females as compared to males. The prevalence of this disease is maximum in third and fourth decades of life.

Sex distribution
Age distribution

Pathophysiology

The pathophysiology of thyroid cancer is not completely defined. Transformation of various molecular factors has been linked with thyroid malignancy. These include proliferative factors like growth hormones and oncogenes, and apoptotic and cell-cycle hindering factors such as tumor suppressors [2].

Physiological behavior of the cancer depends upon the type of tumor. Thyroid cancer is thought to follow a continuity from well differentiated to anaplastic, distinguished by early and late genetic events [3]. Many patients suffering from differentiated thyroid cancer experience loss of thyroid-specific functions such as iodine aggregation [4].

Papillary carcinoma arises from follicular cells, that produce and store thyroid hormones, have a tendency of spreading to local lymph nodes. Follicular carcinoma also arises from the follicular cells and Hurthle cell carcinoma is a rare type of follicular carcinoma that spread hematogenously.

Medullary thyroid cancer begins in thyroid cells called C cells that produce the hormone calcitonin. Anaplastic thyroid cancer is a rare, aggressive, undifferentiated carcinoma that is inclined to local invasion and metastatic spread.

Nodal spread is common with thyroid lymphoma which is a rare form of thyroid cancer that begins in the immune system cells in the thyroid and grows very quickly.

Prevention

Exposure to radiation in early childhood is a known risk of thyroid cancer hence it is advised that children should not have any tests involving exposure to radiation unless it is absolutely essential.

Blood tests can be performed to look out for genetic mutations that are seen in familial medullary carcinoma as MTC can be treated early by removing the gland. Once the disease is discovered in the family, all the other family members should be tested for this mutated gene for prevention of cancer.

Summary

Thyroid cancer is a cancer arising from the follicular or parafollicular cells of the thyroid gland. Thyroid cancers can be divided into follicular carcinomas, papillary carcinomas, anaplastic carcinomas, primary thyroid lymphomas, medullary thyroid carcinomas (MTCs), and primary thyroid sarcomas.

Patient Information

Thyroid gland is an essential gland for the normal functioning of the body and hence prompt treatment of the thyroid cancer is needed. Like any other cancer the exact cause is known but childhood radiation has shown to be a risk factor and should be studiously avoided. Being diagnosed as a patient of thyroid cancer can be frightening, but thyroid cancer is curable most of the times.

The cancer is diagnosed by thyroid hormone tests, ultrasound of the neck and maybe CT or MRI scans too. There are various line of treatments that are available now a days to cure this disease.

Depending on the type and stage of cancer the physician guides you to the best mode of treatment that is appropriate for you. After the treatment you will have to take a pill to replace the thyroid hormone in your body for life time.

References

Article

  1. Lozano R, Naghavi M, Foreman K, Lim S, et al. Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. 2012 Dec 15; 380 (9859): 2095–128.
  2. Segev DL, Umbricht C, Zeiger MA. Molecular pathogenesis of thyroid cancer. Surg Oncol. 2003 Aug;12(2):69-90.
  3. Patel KN, Singh B. Genetic considerations in thyroid cancer. Cancer Control. 2006 Apr;13(2):111-118.
  4. Simon D, Korber C, Krausch M, et al. Clinical impact of retinoids in redifferentiation therapy of advanced thyroid cancer: final results of a pilot study. Eur J Nucl Med Mol Imaging. 2002 Jun;29(6):775-782.
  5. Yip L, Wharry LI, Armstrong MJ, Silbermann A, et al. A clinical algorithm for fine-needle aspiration molecular testing effectively guides the appropriate extent of initial thyroidectomy. Ann Surg. 2014 Jul;260(1):163-8.
  6. Kwon H, Kim WG, Choi YM, Jang EK, et al. A cut-off Value of Basal Serum Calcitonin for Detecting Macroscopic Medullary Thyroid Carcinoma. Clin Endocrinol (Oxf). 2014 Jul 19.
  7. Sovrea AS, Dronca E, Galatâr M, Radian S, et al. Diagnostic correlation between RET proto-oncogene mutation, imaging techniques, biochemical markers and morphological examination in MEN2A syndrome: case report and literature review. Rom J Morphol Embryol. 2014;55(2):389-400.
  8. Brooks M. Low-risk thyroid cancer overdiagnosed, overtreated. Medscape Medical News [serial online]. August 28, 2013;Accessed September 1, 2013. Available at http://www.medscape.com/viewarticle/810129.
  9. Brito JP, Morris JC, Montori VM. Thyroid cancer: zealous imaging has increased detection and treatment of low risk tumours. BMJ. 2013 Aug 27;347:f4706.
  10. Fallahi P, Ferrari SM, Mazzi V, Vita R, Benvenga S, Antonelli A. Personalization of targeted therapy in advanced thyroid cancer. Curr Genomics. 2014 Jun;15(3):190-202.

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Last updated: 2019-07-11 22:01