Medullary thyroid cancer | |
---|---|
Other names | MTC |
![]() | |
Micrograph of medullary thyroid carcinoma with amyloid deposition (left of image). Near normal thyroid follicles are also seen (right of image). H&E stain. | |
Specialty | ENT surgery |
Medullary thyroid cancer is a form of thyroid carcinoma which originates from the parafollicular cells (C cells), which produce the hormone calcitonin. [1] Medullary tumors are the third most common of all thyroid cancers and together make up about 3% of all thyroid cancer cases. [2] MTC was first characterized in 1959. [3]
Approximately 25% of medullary thyroid cancer cases are genetic in nature, caused by a mutation in the RET proto-oncogene. When MTC occurs by itself it is termed sporadic medullary thyroid cancer. Medullary thyroid cancer is seen in people with multiple endocrine neoplasia type 2A and 2B. When medullary thyroid cancer due to a hereditary genetic disorder occurs without other endocrine tumours it is termed familial medullary thyroid cancer.
The major clinical symptom of metastatic medullary thyroid carcinoma is diarrhea; occasionally a patient will have flushing episodes. Both occur particularly with liver metastasis, and either symptom may be the first manifestation of the disease. The flushing that occurs in medullary thyroid carcinoma is indistinguishable from that associated with carcinoid syndrome. In MTC, the flushing, diarrhea, and itching (pruritus) are all caused by elevated levels of calcitonin gene products (calcitonin or calcitonin gene-related peptide). [4] By comparison, the flushing and diarrhea observed in carcinoid syndrome is caused by elevated levels of circulating serotonin.
Medullary thyroid carcinoma may also produce a thyroid nodule and enlarged cervical lymph nodes. [4]
Sites of spread of medullary thyroid carcinoma include local lymph nodes in the neck, lymph nodes in the central portion of the chest (mediastinum), liver, lung, and bone. Spread to other sites such as skin or brain occurs but is uncommon.
Mutations (DNA changes) in the RET proto-oncogene, located on chromosome 10, lead to the expression of a mutated receptor tyrosine kinase protein, termed RET (REarranged during Transfection). RET is involved in the regulation of cell growth and development and its germline mutation is responsible for nearly all cases of hereditary or familial medullary thyroid carcinoma. Its germline mutation may also be responsible for the development of hyperparathyroidism and pheochromocytoma. Hereditary medullary thyroid cancer is inherited as an autosomal dominant trait, meaning that each child of an affected parent has a 50% probability of inheriting the mutant RET proto-oncogene from the affected parent. DNA analysis makes it possible to identify children who carry the mutant gene; surgical removal of the thyroid in children who carry the mutant gene is curative if the entire thyroid gland is removed at an early age, before there is spread of the tumor. The parathyroid tumors and pheochromocytomas are removed when they cause clinical symptomatology. Hereditary medullary thyroid carcinoma or multiple endocrine neoplasia (MEN2) accounts for approximately 25% of all medullary thyroid carcinomas.
Seventy-five percent of medullary thyroid carcinoma occurs in individuals without an identifiable family history and is assigned the term "sporadic". Individuals who develop sporadic medullary thyroid carcinoma tend to be older and have more extensive disease at the time of initial presentation than those with a family history (screening is likely to be initiated at an early age in the hereditary form). Approximately 25-60% of sporadic medullary thyroid carcinomas have a somatic mutation (one that occurs within a single "parafollicular" cell) of the RET proto-oncogene. This mutation is presumed to be the initiating event, although there could be other as yet unidentified causes.
While the increased serum concentration of calcitonin is not harmful, it is useful as a marker which can be tested in blood. [5]
A second marker, carcinoembryonic antigen (CEA), also produced by medullary thyroid carcinoma, is released into the blood and it is useful as a serum or blood tumor marker. In general, measurement of serum CEA is less sensitive than serum calcitonin for detecting the presence of a tumor, but has less minute to minute variability and is therefore useful as an indicator of tumor mass.
Diagnosis is primarily performed via fine needle aspiration of the lesion of the thyroid to distinguish it from other types of thyroid lesions. [6] Microscopic examination will show an amyloid stroma with hyperplasia of parafollicular cells.
A recent Cochrane systematic review assessed the diagnostic accuracy of basal and stimulated calcitonin for Medullary Thyroid Carcinoma. [7] Although both basal and combined basal and stimulated calcitonin testing presented high accuracy (sensitivity: between 82% and 100%; specificity: between 97.2% and 100%), these results had a high risk of bias due to design flaws of included studies. [7] Overall, the value of routine testing of calcitonin for diagnosis and prognosis of Medullary Thyroid Carcinoma remains uncertain and questionable. [7]
Surgery and radiation therapy have been the major treatments for medullary thyroid carcinoma. A plasma level of metanephrines should be checked before surgical thyroidectomy takes place to evaluate for the presence of pheochromocytoma since 25% of people found to have medullary thyroid cancer have the inherited form from the MEN2A syndrome. Undiagnosed pheochromocytoma leads to a very high intraoperative risk of hypertensive crisis and, potentially, death.
A total thyroidectomy with bilateral neck dissection is the gold standard for treating medullary thyroid cancer, and is the most definitive means of achieving a cure in patients without distant metastases or extensive nodal involvement. Risks of surgery include loss of vocal control, irreparable nerve damage, death or the need for second operation to clean out residual diseased lymph nodes left behind if the sentinel node biopsy was positive for cancerous spread. Extensive surgery can be effective when the condition is detected early, but a risk for recurrence remains, particularly in patients with multiple positive lymph nodes or extracapsular invasion. [1] [8] About half of patients have metastasis to regional lymph nodes at the time of diagnosis. [4]
The European Society of Endocrine Surgeons has published recommendations for managing this condition in gene carriers. [9] The timing of surgery depends on the type of mutation present. For those in the highest risk group, surgery is recommended in the first year of life. In lower risk cases surgery may be delayed up to the age of ten years, the precise timing depending on the mutation and other factors.
External beam radiotherapy is recommended when there is a high risk of regional recurrence, even after optimum surgical treatment. [10] [11] In this study, patients treated with external beam radiation were compared to a control group. Disease control with radiation was far superior in the group receiving radiation. The authors of the study [14] wrote: "in 40 high risk patients (microscopic residual disease, extraglandular invasion, or lymph node involvement), the local/regional relapse free rate was 86% at 10 years with postoperative external beam radiation (25 patients), and 52% for those with no postoperative external radiation (p = 0.049). To optimize local/regional tumor control, we therefore continue to advise external beam radiation in patients at high risk of local/regional relapse."
Unlike other differentiated thyroid carcinoma, there is no role for radioiodine treatment in medullary-type disease. [12]
Clinical trials of protein kinase inhibitors, [13] which block the abnormal kinase proteins involved in the development and growth of medullary cancer cells, showed clear evidence of response in 10-30% of patients. In the majority of responders there has been less than a 30% decrease in tumor mass, yet the responses have been durable; responses have been stable for periods exceeding 3 years. The major side effects of this class of drug include hypertension, nausea, diarrhea, some cardiac electrical abnormalities, and thrombotic or bleeding episodes.
Vandetanib, trade name Caprelsa, was the first drug (April 2011) to be approved by US Food and Drug Administration (FDA) for treatment of late-stage (metastatic) medullary thyroid cancer in adult patients who are ineligible for surgery. [14]
Cabozantinib, trade name Cometriq, was granted marketing approval (November 2012) by the U.S. FDA for this indication. [15] Cabozantinib which is a potent inhibitor of RET, MET and VEGF was evaluated in a double-blind placebo controlled trial. It was shown to improve overall survival by 5 months for the treated cohort vs. placebo, which was not statistically significant. However, cabozantinib was particularly effective in patients with the RET M918T mutation, extending overall survival by roughly 2 years, doubling survival vs. untreated patient (4 years vs. 2 year). Treatment with cabozantinib did require many dose reduction to mitigate side effects. It has been suggested that the trial dose of 140 mg was excessive, particularly in lower body mass patients. Ongoing trials have been scheduled to identify more optimal dosing regimes. Activity has been observed, in practice at doses of 1.2 mg/kg.
Depending on source, the overall 5-year survival rate for medullary thyroid cancer is 80%, [16] 83% [17] or 86%, [6] and the 10-year survival rate is 75%. [16]
By overall cancer staging into stages I to IV, the 5-year survival rate is 100% at stage I, 98% at stage II, 81% at stage III and 28% at stage IV. [18] The prognosis of MTC is poorer than that of follicular and papillary thyroid cancer when it has metastasized (spread) beyond the thyroid gland.
The prognostic value of measuring calcitonin and carcinoembryonic antigen (CEA) concentrations in the blood was studied in 65 MTC patients who had abnormal calcitonin levels after surgery (total thyroidectomy and lymph node dissection). [19] The prognosis correlated with the rate at which the postoperative calcitonin concentration doubles, termed the calcitonin doubling time (CDT), rather than the pre- or postoperative absolute calcitonin level:
The calcitonin doubling time was a better predictor of MTC survival than CEA [19] but following both tests is recommended. [10] [20]
Mastectomy is the medical term for the surgical removal of one or both breasts, partially or completely. A mastectomy is usually carried out to treat breast cancer. In some cases, women believed to be at high risk of breast cancer have the operation as a preventive measure. Alternatively, some women can choose to have a wide local excision, also known as a lumpectomy, an operation in which a small volume of breast tissue containing the tumor and a surrounding margin of healthy tissue is removed to conserve the breast. Both mastectomy and lumpectomy are referred to as "local therapies" for breast cancer, targeting the area of the tumor, as opposed to systemic therapies, such as chemotherapy, hormonal therapy, or immunotherapy.
Thyroid neoplasm is a neoplasm or tumor of the thyroid. It can be a benign tumor such as thyroid adenoma, or it can be a malignant neoplasm, such as papillary, follicular, medullary or anaplastic thyroid cancer. Most patients are 25 to 65 years of age when first diagnosed; women are more affected than men. The estimated number of new cases of thyroid cancer in the United States in 2010 is 44,670 compared to only 1,690 deaths. Of all thyroid nodules discovered, only about 5 percent are cancerous, and under 3 percent of those result in fatalities.
Multiple endocrine neoplasia is a condition which encompasses several distinct syndromes featuring tumors of endocrine glands, each with its own characteristic pattern. In some cases, the tumors are malignant, in others, benign. Benign or malignant tumors of nonendocrine tissues occur as components of some of these tumor syndromes.
Calcitonin is a 32 amino acid peptide hormone secreted by parafollicular cells (also known as C cells) of the thyroid (or endostyle) in humans and other chordates in the ultimopharyngeal body. It acts to reduce blood calcium (Ca2+), opposing the effects of parathyroid hormone (PTH).
Adrenocortical carcinoma (ACC) is an aggressive cancer originating in the cortex of the adrenal gland.
Pentagastrin is a synthetic polypeptide that has effects like gastrin when given parenterally. It stimulates the secretion of gastric acid, pepsin, and intrinsic factor, and has been used as a diagnostic aid as the pentagastrin-stimulated calcitonin test.
This is a list of terms related to oncology. The original source for this list was the US National Cancer Institute's public domain Dictionary of Cancer Terms.
Multiple endocrine neoplasia type 2 is a group of medical disorders associated with tumors of the endocrine system. The tumors may be benign or malignant (cancer). They generally occur in endocrine organs, but may also occur in endocrine tissues of organs not classically thought of as endocrine. MEN2 is a sub-type of MEN and itself has sub-types, as discussed below. Variants in MEN2A have been associated with Hirschsprung disease. Screening for this condition can begin as young as eight years old for Pheochromocytoma.
A Hürthle cell is a cell in the thyroid that is often associated with Hashimoto's thyroiditis as well as benign and malignant tumors. This version is a relatively rare form of differentiated thyroid cancer, accounting for only 3-10% of all differentiated thyroid cancers. Oncocytes in the thyroid are often called Hürthle cells. Although the terms oncocyte, oxyphilic cell, and Hürthle cell are used interchangeably, Hürthle cell is used only to indicate cells of thyroid follicular origin.
Anaplastic thyroid cancer (ATC), also known as anaplastic thyroid carcinoma, is an aggressive form of thyroid cancer characterized by uncontrolled growth of cells in the thyroid gland. This form of cancer generally carries a very poor prognosis due to its aggressive behavior and resistance to cancer treatments. The cells of anaplastic thyroid cancer are highly abnormal and usually no longer resemble the original thyroid cells and have poor differentiation.
Papillary thyroid cancer is the most common type of thyroid cancer, representing 75 percent to 85 percent of all thyroid cancer cases. It occurs more frequently in women and presents in the 20–55 year age group. It is also the predominant cancer type in children with thyroid cancer, and in patients with thyroid cancer who have had previous radiation to the head and neck. It is often well-differentiated, slow-growing, and localized, although it can metastasize.
Nasopharyngeal carcinoma (NPC), or nasopharynx cancer, is the most common cancer originating in the nasopharynx, most commonly in the postero-lateral nasopharynx or pharyngeal recess, accounting for 50% of cases. NPC occurs in children and adults. NPC differs significantly from other cancers of the head and neck in its occurrence, causes, clinical behavior, and treatment. It is vastly more common in certain regions of East Asia and Africa than elsewhere, with viral, dietary and genetic factors implicated in its causation. It is most common in males. It is a squamous cell carcinoma of an undifferentiated type. Squamous epithelial cells are a flat type of cell found in the skin and the membranes that line some body cavities. Undifferentiated cells are cells that do not have their mature features or functions.
The RETproto-oncogene encodes a receptor tyrosine kinase for members of the glial cell line-derived neurotrophic factor (GDNF) family of extracellular signalling molecules. RET loss of function mutations are associated with the development of Hirschsprung's disease, while gain of function mutations are associated with the development of various types of human cancer, including medullary thyroid carcinoma, multiple endocrine neoplasias type 2A and 2B, pheochromocytoma and parathyroid hyperplasia.
Multiple endocrine neoplasia type 2B is a genetic disease that causes multiple tumors on the mouth, eyes, and endocrine glands. It is the most severe type of multiple endocrine neoplasia, differentiated by the presence of benign oral and submucosal tumors in addition to endocrine malignancies. It was first described by Wagenmann in 1922, and was first recognized as a syndrome in 1965-1966 by E.D. Williams and D.J. Pollock. It is caused by the pathogenic variant p.Met918Thr in the RET gene. This variant can cause medullary thyroid cancer and Pheochromocytoma. Presentation can include a Marfanoid body, enlarged lips, and ganglionueuromas.
Parathyroid carcinoma is a rare cancer resulting in parathyroid adenoma to carcinoma progression. It forms in tissues of one or more of the parathyroid glands.
Male breast cancer (MBC) is a cancer in males that originates in their breasts. Males account for less than 1% of new breast cancers with about 20,000 new cases being diagnosed worldwide every year. Its incidence rates in males vs. females are, respectively, 0.4 and 66.7 per 100,000 person-years. The worldwide incidences of male as well as female breast cancers have been increasing over the last few decades. Currently, one of every 800 men are estimated to develop this cancer during their lifetimes.
Renal medullary carcinoma is a rare type of cancer that affects the kidney. It tends to be aggressive, difficult to treat, and is often metastatic at the time of diagnosis. Most individuals with this type of cancer have sickle cell trait or rarely sickle cell disease, suggesting that the sickle cell trait may be a risk factor for this type of cancer.
Thyroid cancer is cancer that develops from the tissues of the thyroid gland. It is a disease in which cells grow abnormally and have the potential to spread to other parts of the body. Symptoms can include swelling or a lump in the neck. Cancer can also occur in the thyroid after spread from other locations, in which case it is not classified as thyroid cancer.
Selpercatinib, sold under the brand name Retevmo among others, is a medication for the treatment of cancers in people whose tumors have an alteration in a specific gene. It is taken by mouth.
Mammary secretory carcinoma (MSC), also termed secretory carcinoma of the breast, is a rare form of the breast cancers. MSC usually affects women but in a significant percentage of cases also occurs in men and children. Indeed, McDvitt and Stewart first described MSC in 1966 and termed it juvenile breast carcinoma because an increased number of cases were at that time diagnosed in juvenile females. MSC is the most common form of breast cancer in children, representing 80% of childhood breast cancers, although it accounts for less than 0.15% of all breast cancers.