This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the treatment of childhood thyroid cancer. It is intended as a resource to inform and assist clinicians who care for cancer patients. It does not provide formal guidelines or recommendations for making health care decisions.

This summary is reviewed regularly and updated as necessary by the PDQ Pediatric Treatment Editorial Board, which is editorially independent of the National Cancer Institute (NCI). The summary reflects an independent review of the literature and does not represent a policy statement of NCI or the National Institutes of Health (NIH).

Incidence

The annual incidence of thyroid cancers is 4.8 to 5.9 cases per 1 million people aged 0 to 19 years, accounting for approximately 1.5% of all cancers in this age group.[1,2] Thyroid cancer incidence is higher in children aged 15 to 19 years (17.6 cases per 1 million people), and it accounts for approximately 8% of cancers arising in this older age group.[1,3] More thyroid carcinomas occur in females than in males.[4] Two time-trend studies using the Surveillance, Epidemiology, and End Results (SEER) database have shown a 2% and 3.8% annual increase in the incidence of differentiated thyroid carcinoma in the United States among children, adolescents, and young adults in the 1973 to 2011 and 1984 to 2010 periods, respectively.[1,5] A similar trend towards an increase in the incidence of thyroid cancer among children, adolescents, and young adults over the last two decades has been documented in Canada.[6] The trend toward larger tumors suggests that diagnostic scrutiny is not the only explanation for the observed results.[5]

The incidence is higher in whites (5.3 cases per 1 million vs. 1.5 cases per 1 million in blacks) and female adolescents (8.1 cases per 1 million vs. 1.7 cases per 1 million in male adolescents).[1]

The papillary subtype is the most common, accounting for approximately 60% of the cases, followed by the papillary follicular variant subtype (20%–25%), the follicular subtype (10%), and the medullary subtype (<10%).The incidence of the papillary subtype and its follicular variant peaks between the ages of 15 and 19 years. The incidence of medullary thyroid cancer is the highest in the age group of 0 to 4 years and declines at older ages (refer to Figure 1).[2]

Figure 1. Incidence of pediatric thyroid carcinoma based on most frequent subtype per 100,000 as a percent of total cohort. Reprinted from International Journal of Pediatric Otorhinolaryngology, Volume 89, Sarah Dermody, Andrew Walls, Earl H. Harley Jr., Pediatric thyroid cancer: An update from the SEER database 2007–2012, Pages 121–126, Copyright (2016), with permission from Elsevier.

Risk Factors

Risk factors for pediatric thyroid cancer include the following:

• Radiation exposure. There is an excessive frequency of papillary thyroid adenoma and carcinoma after radiation exposure, either as result of environmental contamination or use of ionizing radiation for diagnosis or treatment.[1-4] (Refer to the Subsequent Neoplasms section of the PDQ summary on Late Effects of Treatment for Childhood Cancer for more information.) The risk increases after exposure to a mean dose of more than 0.05 Gy to 0.1 Gy (50–100 mGy), and follows a linear dose-response pattern up to 30 Gy and then declines, which is greater at younger age of exposure and persists more than 45 years after exposure.[4,5] Papillary thyroid carcinoma is the most frequent form of thyroid carcinoma diagnosed after radiation exposure.[5] Molecular alterations, including intrachromosomal rearrangements, are frequently found; among them, RET/PTC rearrangements are the most common.[5]
• Genetic inheritance. Genetic inheritance plays a role in a subset of thyroid carcinomas. In children, medullary thyroid carcinoma is caused by a dominantly inherited or de novo gain-of-function mutation in the RET proto-oncogene associated with multiple endocrine neoplasia (MEN) type 2, either MEN2A or MEN2B, depending on the specific mutation.[6] When occurring in patients with the MEN syndromes, thyroid cancer may be associated with the development of other types of malignant tumors. (Refer to the Multiple Endocrine Neoplasia [MEN] Syndromes and Carney Complex section of the PDQ summary on Unusual Cancers of Childhood Treatment for more information.)
• Family history. For thyroid carcinomas of follicular cells, only 5% to 10% are familial cancers. Of those, only a minority occur in the setting of well-defined cancer syndromes with known germline alterations (APC-associated polyposis, Carney complex, PTEN hamartoma tumor syndrome, Werner syndrome, and DICER1 syndrome), while most familial cases are nonsyndromic.[7,8]

Histology

Tumors of the thyroid are classified as adenomas or carcinomas.[1-3] Adenomas are benign, well circumscribed and encapsulated nodules that may cause enlargement of all or part of the gland, which extends to both sides of the neck and can be quite large; some tumors may secrete hormones. Transformation to a malignant carcinoma may occur in some cells, which may grow and spread to lymph nodes in the neck or to the lungs. Approximately 20% of thyroid nodules in children are malignant.[1,4]

The following histologies account for the general diagnostic category of carcinoma of the thyroid:

• Differentiated thyroid carcinoma: Papillary and follicular carcinoma are often referred to as differentiated thyroid carcinoma. The pathological classification of differentiated thyroid carcinomas in children is based on standard definitions set by the World Health Organization, and the criteria are the same for children and adults. Long-term outcomes for children and adolescents with differentiated thyroid carcinoma are excellent, with 10-year survival rates exceeding 95%.[4-6]

  • Papillary thyroid carcinoma: Papillary thyroid carcinoma accounts for 90% or more of all cases of differentiated thyroid carcinoma occurring during childhood and adolescence. Pediatric papillary thyroid carcinoma may present with a variety of histological variants: classic, solid, follicular, and diffuse sclerosing. Papillary thyroid carcinoma is frequently multifocal and bilateral, and metastasizes to regional lymph nodes in most children. Hematogenous metastases to the lungs occur in up to 25% of cases.[4]
  • Follicular thyroid cancer: Follicular thyroid cancer is uncommon. It is typically a unifocal tumor and more prone to initial hematogenous metastases to lungs and bones. Metastases to regional lymph nodes are uncommon. Histologic variants of follicular thyroid cancer include Hürthle cell (oncocytic), clear cell, and insular (poorly differentiated) carcinoma.[4]
• Medullary thyroid carcinoma: Medullary thyroid carcinoma is a rare form of thyroid carcinoma that originates from the calcitonin-secreting parafollicular C cells and accounts for less than 10% of all cases of thyroid carcinoma in children.[6] In children, medullary thyroid carcinoma is usually associated with RET germline mutations in the context of multiple endocrine neoplasia type 2 syndrome.[7]
• Anaplastic carcinoma: Less than 1% of pediatric thyroid carcinomas are anaplastic carcinoma.

Molecular Features

Clinical Presentation and Outcome

Diagnostic Evaluation

Initial evaluation of a child or adolescent with a thyroid nodule includes the following:

• Ultrasound of the thyroid.
• Serum thyroid-stimulating hormone (TSH) level.
• Serum thyroglobulin level.

Tests of thyroid function are usually normal, but thyroglobulin can be elevated.

Fine-needle aspiration as an initial diagnostic approach is sensitive and useful. However, in doubtful cases, open biopsy or resection should be considered.[1].

Treatment of Papillary and Follicular Thyroid Carcinoma

Treatment options for papillary and follicular (differentiated) thyroid carcinoma may include the following:

1. Surgery.
2. Radioactive iodine ablation.

In 2015, the American Thyroid Association (ATA) Task Force on Pediatric Thyroid Cancer published guidelines for the management of thyroid nodules and differentiated thyroid cancer in children and adolescents. These guidelines (summarized below) are based on scientific evidence and expert panel opinion, with a careful assessment of the level of evidence.[1]

1. Preoperative evaluation.[1]

   1. A comprehensive ultrasound of all regions of the neck using a high-resolution probe and Doppler technique should be obtained by an experienced ultrasonographer. A complete ultrasound examination should be performed before surgery.
   2. The addition of cross-sectional imaging (contrast-enhanced computed tomography [CT] or magnetic resonance imaging) should be considered when there is concern about invasion of the aerodigestive tract. Importantly, if iodinated contrast agents are used, further evaluation and treatment with radioactive iodine may need to be delayed for 2 to 3 months until total body iodine burden decreases.
   3. Chest imaging (x-ray or CT) may be considered for patients with substantial cervical lymph node disease.
   4. Thyroid nuclear scintigraphy should be pursued only if the patient presents with a suppressed thyroid-stimulating hormone (TSH).
   5. The routine use of bone scan or fluorine F 18-fludeoxyglucose positron emission tomography (PET) is not recommended.
2. Surgery.[1]
   Pediatric thyroid surgery is ideally completed by a surgeon who has experience performing endocrine procedures in children and in a hospital with the full spectrum of pediatric specialty care.

   1. Thyroidectomy:
      For patients with papillary or follicular carcinoma, total thyroidectomy is the recommended treatment of choice. The ATA expert panel recommendation is based on data showing an increased incidence of bilateral (30%) and multifocal (65%) disease.
      In patients with a small unilateral tumor confined to the gland, a near-total thyroidectomy—whereby a small amount of thyroid tissue (<1%–2%) is left in place at the entry point of the recurrent laryngeal nerve or superior parathyroid glands—might be considered to decrease permanent damage to those structures.
      Total thyroidectomy also optimizes the use of radioactive iodine for imaging and treatment.
   2. Central neck dissection:

      • A therapeutic central neck lymph node dissection should be done in the presence of clinical evidence of central or lateral neck metastases.[2]
      • For patients without clinical evidence of gross extrathyroidal invasion or locoregional metastasis, a prophylactic central neck dissection may be considered on the basis of tumor focality and size of the primary tumor. However, because of the increased morbidity associated with central lymph node dissection, it is important to carefully individualize each case on the basis of the risks and benefits of the extent of dissection.[3]
   3. Lateral neck dissection:

      • Cytological confirmation of metastatic disease to lymph nodes in the lateral neck is recommended before surgery.
      • Routine prophylactic lateral neck dissection is not recommended.
3. Classification and risk assignment.[1]
   Despite the limited data in pediatrics, the ATA Task Force recommends the use of the tumor-node-metastasis (TNM) classification system to categorize patients into one of three risk groups. (Refer to the Stage Information for Thyroid Cancer section in the PDQ summary on Thyroid Cancer Treatment [Adult] for more information about the TNM system.) This categorization strategy is meant to define the risk of persistent cervical disease and help determine which patients should undergo postoperative staging for the presence of distant metastasis.

   1. ATA Pediatric Low Risk: Disease confined to the thyroid with N0 or NX disease or patients with incidental N1a (microscopic metastasis to a small number of central neck nodes). These patients are at lowest risk of distant disease but may still be at risk of residual cervical disease, especially if the initial surgery did not include central neck dissection.
   2. ATA Pediatric Intermediate Risk: Extensive N1a or minimal N1b disease. These patients are at low risk of distant metastasis but are at an increased risk of incomplete lymph node resection and persistent cervical disease.
   3. ATA Pediatric High Risk: Regionally extensive disease (N1b) or locally invasive disease (T4), with or without distant metastasis. Patients in this group are at the highest risk of incomplete resection, persistent disease, and distant metastasis.
4. Postoperative staging and long-term surveillance.[1]
   Initial staging should be performed within 12 weeks after surgery; the purpose is to assess for evidence of persistent locoregional disease and to identify patients who are likely to benefit from additional therapy with iodine I 131 (131I). The ATA Pediatric Risk Level (as defined above) helps determine the extent of postoperative testing.

   1. ATA Pediatric Low Risk:

      • Initial postoperative staging includes a TSH-suppressed thyroglobulin. A diagnostic iodine I 123 (123I) scan is not required.
      • TSH suppression should be targeted to serum levels of 0.5 to 1.0 mIU/L.
      • In patients with no evidence of disease, surveillance should include ultrasound at 6 months postoperatively and then annually for 5 years; and thyroglobulin levels (on hormone replacement therapy) every 3 to 6 months for 2 years and then annually.
   2. ATA Pediatric Intermediate Risk:

      • Initial postoperative staging includes a TSH-stimulated thyroglobulin and diagnostic 123I whole-body scan for further stratification and determination with 131I.
      • TSH suppression should be targeted to serum levels of 0.1 to 0.5 mIU/L.
      • In patients with no evidence of disease, surveillance should include ultrasound at 6 months postoperatively and then every 6 to 12 months for 5 years (and then less frequently); and thyroglobulin levels (on hormone replacement therapy) every 3 to 6 months for 3 years and then annually.
      • TSH-stimulated thyroglobulin and diagnostic 123I scan should be considered in 1 to 2 years for patients treated with 131I.
   3. ATA Pediatric High Risk:

      • Initial postoperative staging includes a TSH-stimulated thyroglobulin and diagnostic 123I whole-body scan for further stratification and determination with 131I.
      • TSH suppression should be targeted to serum levels of less than 0.1 mIU/L.
      • In patients with no evidence of disease, surveillance should include ultrasound at 6 months postoperatively and then every 6 to 12 months for 5 years (and then less frequently); and thyroglobulin levels (on hormone replacement therapy) every 3 to 6 months for 3 years and then annually.
      • TSH-stimulated thyroglobulin and, possibly, a diagnostic 123I scan in 1 to 2 years in patients treated with 131I.
   For patients with antithyroglobulin antibodies, consideration can be given to deferred postoperative staging to allow time for antibody clearance, except in patients with T4 or M1 disease.
5. Radioactive iodine ablation.[1]
   The goal of 131I therapy is to decrease the risks of recurrence and to decrease mortality by eliminating iodine-avid disease.

   1. The ATA Task Force recommends the use of 131I for the treatment of iodine-avid persistent locoregional or nodal disease that cannot be resected and known or presumed iodine-avid distant metastases. For patients with persistent disease after administration of 131I, the decision to pursue additional 131I therapy should be individualized on the basis of clinical data and previous response.
   2. To facilitate 131I uptake by residual iodine-avid disease, the TSH level should be above 30 mIU/L. This level can be achieved by withdrawing levothyroxine for at least 14 days. In patients who cannot mount an adequate TSH response or cannot tolerate profound hypothyroidism, recombinant human TSH may be used.
   3. Therapeutic 131I administration is commonly based on either empiric dosing or whole-body dosimetry. Based on the lack of data comparing empiric treatment and treatment informed by dosimetry, the ATA Task Force was unable to recommend one specific approach. However, because of the differences in body size and iodine clearance in children compared with adults, it is recommended that all activities of 131I should be calculated by experts with experience in dosing children.
   4. A posttreatment whole-body scan is recommended for all children 4 to 7 days after 131I therapy. The addition of single-photon emission CT with integrated conventional CT (SPECT/CT) may help to distinguish the anatomic location of focal uptake.
      While rare, late effects of 131I treatment include salivary gland dysfunction, bone marrow suppression, pulmonary fibrosis, and second malignancies.[4]

Treatment of Recurrent Papillary and Follicular Thyroid Carcinoma

Despite the more advanced disease at presentation compared with adults, children with differentiated thyroid cancer generally have an excellent survival with relatively few side effects.[1-3]

Radioactive iodine ablation with iodine I 131 (131I) is usually effective after recurrence.[4] For patients with 131I-refractory disease, molecularly targeted therapies using kinase inhibitors may provide alternative therapies.

Tyrosine kinase inhibitors (TKIs) with documented efficacy for the treatment of adults include the following:

• Sorafenib. Sorafenib is a vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), and RAS kinase inhibitor. In a randomized phase III trial, sorafenib improved progression-free survival (PFS) when compared with placebo (10.8 months vs. 5.8 months) in adult patients with radioactive iodine–refractory locally advanced or metastatic differentiated thyroid cancer.[5] Pediatric-specific data are very limited; however, in one case report, sorafenib produced a radiographic response in a patient aged 8 years with metastatic papillary thyroid carcinoma.[6] Sorafenib was approved by the U.S. Food and Drug Administration (FDA) in November 2013 for the treatment of adults with late-stage metastatic differentiated thyroid carcinoma.
• Lenvatinib. Lenvatinib is an oral VEGFR, fibroblast growth factor receptor, PDGFR, RET, and KIT inhibitor. In a phase III randomized study of adults with 131I-refractory differentiated thyroid cancer, lenvatinib was associated with a significant improvement in PFS and response rate when compared with a placebo.[7] Lenvatinib was approved by the FDA in February 2015 for the treatment of adults with progressive radioactive iodine–refractory differentiated thyroid carcinoma.
• BRAF inhibitors. In an open-label, nonrandomized phase II study of vemurafenib in adult patients with 131I-refractory metastatic or unresectable BRAF-V600E positive papillary thyroid carcinoma who had not been previously treated with a TKI, a response rate of 38.5% was documented.[8] For patients with metastatic or advanced BRAF V600E–mutated anaplastic thyroid carcinoma, the combination of dabrafenib with the MEK inhibitor trametinib has shown a response rate of 69%.[9]

(Refer to the PDQ summary on Thyroid Cancer Treatment [Adult] for more information.)

Treatment of Medullary Thyroid Carcinoma

Medullary thyroid carcinomas are commonly associated with the multiple endocrine neoplasia type 2 (MEN2) syndrome (refer to the Multiple Endocrine Neoplasia [MEN] Syndromes and Carney Complex section of the PDQ summary on Unusual Cancers of Childhood Treatment for more information). They present with a more aggressive clinical course; 50% of the cases have hematogenous metastases at diagnosis.[1] A natural history study of children and young adults with medullary thyroid cancer is being conducted by the National Cancer Institute (NCT01660984). For patients with de novo RET mutations and no familial history, nonendocrine manifestations, such as intestinal ganglioneuromatosis or skeletal or ocular stigmata, may facilitate early diagnosis and result in better outcomes.[2]

Treatment options for medullary thyroid carcinoma include the following:

1. Surgery: Treatment for children with medullary thyroid carcinoma is mainly surgical. A review of 430 patients aged 0 to 21 years with medullary thyroid cancer reported that older age (16–21 years) at diagnosis, tumor diameter greater than 2 cm, positive margins after total thyroidectomy, and lymph node metastases were associated with a worse prognosis.[3] Investigators have concluded that prophylactic central node dissection should not be performed on patients with hereditary medullary thyroid cancer if their basal calcitonin serum levels are lower than 40 pg/mL.[4]
   Most cases of medullary thyroid carcinoma in children occur in the context of the MEN2A and MEN2B syndromes. In those familial cases, early genetic testing and counseling is indicated, and prophylactic surgery is recommended for children with the RET germline mutation. Strong genotype-phenotype correlations have facilitated the development of guidelines for intervention, including screening and age at which prophylactic thyroidectomy should occur. The American Thyroid Association has proposed the following guidelines for prophylactic thyroidectomy in children with hereditary medullary thyroid carcinoma (refer to Table 1).[2]

   Table 1. Risk Levels and Management Based on Common RET Mutations Detected on Genetic Screening^a

   View in own window

   	Medullary Thyroid Carcinoma Risk Level
   	Highest (MEN2B)	High (MEN2A)	Moderate (MEN2A)
   RET Mutation	M918T	A883F, C634F/G/R/S/W/Y	G533C, C609F/G/R/S/Y, C611F/G/S/Y/W, C618F/R/S, C620F/R/S, C630R/Y, D631Y, K666E, E768D, L790F, V804L, V804M, S891A, R912P
   Age for Prophylactic Thyroidectomy	Total thyroidectomy in the first year of life, ideally before age 5 y. Risk of metastasis increases after age 5 y.	Total thyroidectomy at or before age 5 y based on serum calcitonin levels.	Total thyroidectomy to be performed when the serum calcitonin level is above the normal range or at convenience if the parents do not wish to embark on a lengthy period of surveillance.

   MEN2A = multiple endocrine neoplasia type 2A; MEN2B = multiple endocrine neoplasia type 2B.

   ^aAdapted from Wells et al.[2]

2. Tyrosine kinase inhibitor (TKI) therapy: A number of TKIs have been evaluated and approved for patients with advanced thyroid carcinoma.

   • Vandetanib. Vandetanib (an inhibitor of RET kinase, vascular endothelial growth factor receptor [VEGFR], and epidermal growth factor receptor signaling) is approved by the U.S. Food and Drug Administration (FDA) for the treatment of symptomatic or progressive medullary thyroid cancer in adult patients with unresectable, locally advanced, or metastatic disease. Approval was based on a randomized, placebo-controlled, phase III trial that showed a marked progression-free survival (PFS) improvement for patients randomly assigned to receive vandetanib (hazard ratio, 0.35); the trial also showed an objective response rate advantage for patients receiving vandetanib (44% vs. 1% for the placebo arm).[5,6]
     Children with locally advanced or metastatic medullary thyroid carcinoma were treated with vandetanib in a phase I/II trial. Of 16 patients, only 1 had no response, and 7 had a partial response, for an objective response rate of 44%. Disease in three of those patients subsequently recurred, but 11 of 16 patients treated with vandetanib remained on therapy at the time of the report. The median duration of therapy for the entire cohort was 27 months, with a range of 2 to 52 months.[7] A long-term outcome evaluation in a cohort of 17 children and adolescents with advanced medullary thyroid carcinoma who received vandetanib reported a median PFS of 6.7 years and a 5-year overall survival of 88.2%.[8]
   • Cabozantinib. Cabozantinib (an inhibitor of the RET and MET kinases and VEGFR) has also shown activity against unresectable medullary thyroid cancer (10 of 35 adult patients [29%] had a partial response).[9] Cabozantinib was approved by the FDA in November 2012 for the treatment of adults with metastatic medullary thyroid cancer.

(Refer to the Multiple Endocrine Neoplasia [MEN] Syndromes and Carney Complex section of the PDQ summary on Unusual Cancers of Childhood Treatment and the Treatment for those with MTC section in the PDQ summary on Genetics of Endocrine and Neuroendocrine Neoplasias for more information.)

Special Considerations for the Treatment of Children With Cancer

Cancer in children and adolescents is rare, although the overall incidence of childhood cancer has been slowly increasing since 1975.[1] Referral to medical centers with multidisciplinary teams of cancer specialists experienced in treating cancers that occur in childhood and adolescence should be considered for children and adolescents with cancer. This multidisciplinary team approach incorporates the skills of the following health care professionals and others to ensure that children receive treatment, supportive care, and rehabilitation that will achieve optimal survival and quality of life:

• Primary care physicians.
• Pediatric surgeons.
• Radiation oncologists.
• Pediatric medical oncologists/hematologists.
• Rehabilitation specialists.
• Pediatric nurse specialists.
• Social workers.
• Child-life professionals.
• Psychologists.

(Refer to the PDQ Supportive and Palliative Care summaries for specific information about supportive care for children and adolescents with cancer.)

Guidelines for pediatric cancer centers and their role in the treatment of pediatric patients with cancer have been outlined by the American Academy of Pediatrics.[2] At these pediatric cancer centers, clinical trials are available for most types of cancer that occur in children and adolescents, and the opportunity to participate in these trials is offered to most patients and their families. Clinical trials for children and adolescents diagnosed with cancer are generally designed to compare potentially better therapy with therapy that is currently accepted as standard. Most of the progress made in identifying curative therapy for childhood cancers has been achieved through clinical trials. Information about ongoing clinical trials is available from the NCI website.

Dramatic improvements in survival have been achieved for children and adolescents with cancer. Between 1975 and 2010, childhood cancer mortality decreased by more than 50%.[3] Childhood and adolescent cancer survivors require close monitoring because cancer therapy side effects may persist or develop months or years after treatment. (Refer to the PDQ summary on Late Effects of Treatment for Childhood Cancer for specific information about the incidence, type, and monitoring of late effects in childhood and adolescent cancer survivors.)

Childhood cancer is a rare disease, with about 15,000 cases diagnosed annually in the United States in individuals younger than 20 years.[4] The U.S. Rare Diseases Act of 2002 defines a rare disease as one that affects populations smaller than 200,000 persons and, by definition, all pediatric cancers are considered rare. The designation of a pediatric rare tumor is not uniform among international groups, as follows:

• The Italian Rare Tumors in Pediatric Age (TREP) cooperative project defines a pediatric rare tumor as one with an incidence of less than two cases per 1 million population per year and is not included in other clinical trials.[5]
• The Children's Oncology Group has opted to define rare pediatric cancers as those listed in the International Classification of Childhood Cancer subgroup XI, which includes thyroid cancer, melanoma and nonmelanoma skin cancers, and multiple types of carcinomas (e.g., adrenocortical carcinoma, nasopharyngeal carcinoma, and most adult-type carcinomas such as breast cancer, colorectal cancer, etc.).[6] These diagnoses account for about 4% of cancers diagnosed in children aged 0 to 14 years, compared with about 20% of cancers diagnosed in adolescents aged 15 to 19 years.[7] Most cancers within subgroup XI are either melanomas or thyroid cancer, with the remaining subgroup XI cancer types accounting for only 1.3% of cancers in children aged 0 to 14 years and 5.3% of cancers in adolescents aged 15 to 19 years.

These rare cancers are extremely challenging to study because of the low incidence of patients with any individual diagnosis, the predominance of rare cancers in the adolescent population, and the lack of clinical trials for adolescents with rare cancers.

Information about these tumors may also be found in sources relevant to adults with cancer such as the PDQ summary on Thyroid Cancer Treatment (Adult).

Changes to This Summary (08/28/2018)

The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.

This summary was comprehensively reviewed and extensively revised.

This summary is written and maintained by the PDQ Pediatric Treatment Editorial Board, which is editorially independent of NCI. The summary reflects an independent review of the literature and does not represent a policy statement of NCI or NIH. More information about summary policies and the role of the PDQ Editorial Boards in maintaining the PDQ summaries can be found on the About This PDQ Summary and PDQ® - NCI's Comprehensive Cancer Database pages.

About This PDQ Summary