General Information About Childhood Thymoma and Thymic Carcinoma

Thymoma and thymic carcinoma originate within the epithelial cells of the thymus, resulting in an anterior mediastinal mass. The term thymoma is customarily used to describe neoplasms that show no overt atypia of the epithelial component.[1]

Thymic carcinoma or type C thymoma is a thymic epithelial tumor that exhibits clear-cut cytological atypia and histological features no longer specific to the thymus. Thymic carcinomas have a higher incidence of capsular invasion and metastases.[1,2,3]

Other tumors that involve the thymus gland include lymphomas, germ cell tumors, carcinomas, and carcinoids. Hodgkin lymphoma and non-Hodgkin lymphoma may also involve the thymus and must be differentiated from true thymomas and thymic carcinomas.

References:

1. Suster S, Moran CA: Thymoma classification: current status and future trends. Am J Clin Pathol 125 (4): 542-54, 2006.
2. Carretto E, Inserra A, Ferrari A, et al.: Epithelial thymic tumours in paediatric age: a report from the TREP project. Orphanet J Rare Dis 6: 28, 2011.
3. Kelly RJ, Petrini I, Rajan A, et al.: Thymic malignancies: from clinical management to targeted therapies. J Clin Oncol 29 (36): 4820-7, 2011.

Childhood Thymoma

Incidence

Primary tumors of the thymus are exceptionally rare in children, and very few pediatric studies have been reported.[1,2,3,4] A review of the Surveillance, Epidemiology, and End Results (SEER) Program registry from 1973 to 2008 identified 73 cases of malignant anterior mediastinal tumors in patients younger than 20 years.[2] Of these cases, 32% were thymomas, 29% were non-Hodgkin lymphomas, and 22% were Hodgkin lymphomas.

Clinical Presentation

Childhood thymomas are usually located in the anterior mediastinum and discovered during a routine chest x-ray. Symptoms may include the following:[3]

• Cough.
• Difficulty with swallowing.
• Tightness of the chest.
• Chest pain.
• Shortness of breath.
• Superior vena cava syndrome.

About 40% of adults with thymomas have one or more paraneoplastic disorders during their lifetime.[5,6] The most commonly associated disorder is myasthenia gravis, which occurs in approximately 30% of adult patients and has been reported in children.[5] It is important to recognize whether the patient has myasthenia gravis before a thoracotomy of a suspected thymoma.

Various other paraneoplastic syndromes have been found to be associated with thymomas. These include pure red cell aplasia, hypogammaglobulinemia, nephrotic syndrome, and autoimmune or immune disorders such as scleroderma, dermatomyositis, systemic lupus erythematosus, rheumatoid arthritis, and thyroiditis. Endocrine disorders associated with thymomas include hyperthyroidism, Addison disease, and panhypopituitarism.[5,6,7]

Prognosis

The following studies have reported the outcomes of patients with thymomas:

• A review of the SEER Program registry from 1973 to 2008 identified 73 cases of malignant anterior mediastinal tumors in patients younger than 20 years.[2]
  • At 10 years, patients with thymomas had worse survival than patients with lymphomas.
  • Patients with thymomas who were treated in an earlier era, from 1973 to 1989, had a 10-year survival rate of 18%. Patients who were treated between 1991 and 2008 had a survival rate of 75%.
  • Presence of metastatic disease and treatment without surgery were associated with a worse outcome.
• A review identified 48 published cases of thymomas in patients younger than 18 years. This review excluded studies of patients with thymic carcinomas.[3]
  • The review found an association between stage of disease and survival.
  • The review also suggested guidelines for treatment.
  • The overall 2-year survival rate in this series was 71%.
• The European Cooperative Study Group for Pediatric Rare Tumors identified 16 children with thymomas between 2000 and 2012.[4]
  • Complete resection was achieved in 11 of 16 patients.
  • Fourteen of the 16 patients were alive with no evidence of disease at a median of 5 years from diagnosis.

Treatment of Childhood Thymoma

Treatment options for childhood thymoma include the following:

1. Surgery.
2. Radiation therapy.
3. Chemotherapy.
4. Octreotide.
5. Sunitinib.

Surgery

Surgery is the mainstay of therapy, and an attempt should be made to resect all disease.[8]

Radiation therapy

Thymoma is relatively radiosensitive, and radiation therapy is used for patients with unresectable or incompletely resected invasive disease.[7] Radiation dosage recommendations are based on the age of the child and the extent of tumor invasion. Total doses of 45 Gy to 50 Gy may be used for control of clear or close margins, 54 Gy for microscopically positive margins, and at least 60 Gy for patients with bulky residual disease.[9]

Chemotherapy

Chemotherapy is usually reserved for patients with advanced-stage disease who have not responded to radiation therapy or corticosteroids. Agents that have been effective include doxorubicin, cyclophosphamide, etoposide, cisplatin, ifosfamide, and vincristine.[1,7,10] Responses to regimens containing combinations of some of these agents have ranged from 26% to 100%, and survival rates have been as high as 50%.[9,10,11,12]

Octreotide

Because thymoma shows high uptake of indium In 111–labeled octreotide, trials using this somatostatin analogue have been conducted in patients with refractory disease. In an Eastern Cooperative Oncology Group phase II trial of 42 patients, 4 patients had partial responses to octreotide alone, and 8 patients responded with the addition of prednisone to octreotide.[13]

Sunitinib

In an open-label phase II study of sunitinib in adult patients with refractory thymomas, partial responses were observed in 6% of patients, and stable disease was achieved in 75% of patients.[14]

For more information about the treatment of thymomas, see Thymoma and Thymic Carcinoma Treatment.

Treatment Options Under Clinical Evaluation for Childhood Thymoma

Information about National Cancer Institute (NCI)–supported clinical trials can be found on the NCI website. For information about clinical trials sponsored by other organizations, see the ClinicalTrials.gov website.

References:

1. Carretto E, Inserra A, Ferrari A, et al.: Epithelial thymic tumours in paediatric age: a report from the TREP project. Orphanet J Rare Dis 6: 28, 2011.
2. Allan BJ, Thorson CM, Davis JS, et al.: An analysis of 73 cases of pediatric malignant tumors of the thymus. J Surg Res 184 (1): 397-403, 2013.
3. Fonseca AL, Ozgediz DE, Christison-Lagay ER, et al.: Pediatric thymomas: report of two cases and comprehensive review of the literature. Pediatr Surg Int 30 (3): 275-86, 2014.
4. Stachowicz-Stencel T, Orbach D, Brecht I, et al.: Thymoma and thymic carcinoma in children and adolescents: a report from the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT). Eur J Cancer 51 (16): 2444-52, 2015.
5. Thomas CR, Wright CD, Loehrer PJ: Thymoma: state of the art. J Clin Oncol 17 (7): 2280-9, 1999.
6. Tormoehlen LM, Pascuzzi RM: Thymoma, myasthenia gravis, and other paraneoplastic syndromes. Hematol Oncol Clin North Am 22 (3): 509-26, 2008.
7. Cowen D, Richaud P, Mornex F, et al.: Thymoma: results of a multicentric retrospective series of 149 non-metastatic irradiated patients and review of the literature. FNCLCC trialists. Fédération Nationale des Centres de Lutte Contre le Cancer. Radiother Oncol 34 (1): 9-16, 1995.
8. Tomaszek S, Wigle DA, Keshavjee S, et al.: Thymomas: review of current clinical practice. Ann Thorac Surg 87 (6): 1973-80, 2009.
9. National Comprehensive Cancer Network: NCCN Clinical Practice Guidelines in Oncology: Thymomas and Thymic Carcinoma. Version 2.2018. Fort Washington, Pa: National Comprehensive Cancer Network, 2018 . Available online with free subscription. Last accessed June 04, 2019.
10. Casey EM, Kiel PJ, Loehrer PJ: Clinical management of thymoma patients. Hematol Oncol Clin North Am 22 (3): 457-73, 2008.
11. Giaccone G, Ardizzoni A, Kirkpatrick A, et al.: Cisplatin and etoposide combination chemotherapy for locally advanced or metastatic thymoma. A phase II study of the European Organization for Research and Treatment of Cancer Lung Cancer Cooperative Group. J Clin Oncol 14 (3): 814-20, 1996.
12. Loehrer PJ, Jiroutek M, Aisner S, et al.: Combined etoposide, ifosfamide, and cisplatin in the treatment of patients with advanced thymoma and thymic carcinoma: an intergroup trial. Cancer 91 (11): 2010-5, 2001.
13. Loehrer PJ, Wang W, Johnson DH, et al.: Octreotide alone or with prednisone in patients with advanced thymoma and thymic carcinoma: an Eastern Cooperative Oncology Group phase II trial. J Clin Oncol 22 (2): 293-9, 2004.
14. Thomas A, Rajan A, Berman A, et al.: Sunitinib in patients with chemotherapy-refractory thymoma and thymic carcinoma: an open-label phase 2 trial. Lancet Oncol 16 (2): 177-86, 2015.

Childhood Thymic Carcinoma

Incidence and Prognosis

The European Cooperative Study Group for Pediatric Rare Tumors identified 20 patients with thymic carcinomas between 2000 and 2012.[1] Complete resection was achieved in only one patient, and five patients survived. The 5-year overall survival rate was 21%.

Treatment of Childhood Thymic Carcinoma

Treatment options for childhood thymic carcinoma include the following:

1. Surgery.
2. Radiation therapy.
3. Chemotherapy.
4. Sunitinib.

Surgery

Surgery is the mainstay of therapy, and an attempt should be made to resect all disease.[2]

Radiation therapy

Thymic carcinoma is relatively radiosensitive, and radiation therapy is used for patients with unresectable or incompletely resected invasive disease.[3] Radiation dosage recommendations are based on the age of the child and the extent of tumor invasion. Total doses of 45 Gy to 50 Gy may be used for control of clear or close margins, 54 Gy for microscopically positive margins, and at least 60 Gy for patients with bulky residual disease.[4]

Chemotherapy

Response rates are lower for patients with thymic carcinomas who receive chemotherapy, but 2-year survival rates have been as high as 50%.[5,6,7]

For more information, see the Treatment of Childhood Thymoma section.

Sunitinib

In an open-label phase II study of sunitinib in adult patients with refractory thymic carcinomas, partial responses were observed in 26% of patients, and stable disease was achieved in 65% of patients.[8]

For more information about the treatment of thymic carcinomas in adults, see Thymoma and Thymic Carcinoma Treatment.

Treatment Options Under Clinical Evaluation for Childhood Thymic Carcinoma

Information about National Cancer Institute (NCI)–supported clinical trials can be found on the NCI website. For information about clinical trials sponsored by other organizations, see the ClinicalTrials.gov website.

References:

1. Stachowicz-Stencel T, Orbach D, Brecht I, et al.: Thymoma and thymic carcinoma in children and adolescents: a report from the European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT). Eur J Cancer 51 (16): 2444-52, 2015.
2. Tomaszek S, Wigle DA, Keshavjee S, et al.: Thymomas: review of current clinical practice. Ann Thorac Surg 87 (6): 1973-80, 2009.
3. Cowen D, Richaud P, Mornex F, et al.: Thymoma: results of a multicentric retrospective series of 149 non-metastatic irradiated patients and review of the literature. FNCLCC trialists. Fédération Nationale des Centres de Lutte Contre le Cancer. Radiother Oncol 34 (1): 9-16, 1995.
4. National Comprehensive Cancer Network: NCCN Clinical Practice Guidelines in Oncology: Thymomas and Thymic Carcinoma. Version 2.2018. Fort Washington, Pa: National Comprehensive Cancer Network, 2018 . Available online with free subscription. Last accessed June 04, 2019.
5. Loehrer PJ, Jiroutek M, Aisner S, et al.: Combined etoposide, ifosfamide, and cisplatin in the treatment of patients with advanced thymoma and thymic carcinoma: an intergroup trial. Cancer 91 (11): 2010-5, 2001.
6. Carlson RW, Dorfman RF, Sikic BI: Successful treatment of metastatic thymic carcinoma with cisplatin, vinblastine, bleomycin, and etoposide chemotherapy. Cancer 66 (10): 2092-4, 1990.
7. Stachowicz-Stencel T, Bien E, Balcerska A, et al.: Thymic carcinoma in children: a report from the Polish Pediatric Rare Tumors Study. Pediatr Blood Cancer 54 (7): 916-20, 2010.
8. Thomas A, Rajan A, Berman A, et al.: Sunitinib in patients with chemotherapy-refractory thymoma and thymic carcinoma: an open-label phase 2 trial. Lancet Oncol 16 (2): 177-86, 2015.

Special Considerations for the Treatment of Children With Cancer

Cancer in children and adolescents is rare, although the overall incidence has slowly increased since 1975.[1] Children and adolescents with cancer should be referred to medical centers that have a multidisciplinary team of cancer specialists with experience treating the cancers that occur during childhood and adolescence. This multidisciplinary team approach incorporates the skills of the following pediatric specialists and others to ensure that children receive treatment, supportive care, and rehabilitation to achieve optimal survival and quality of life:

• Primary care physicians.
• Pediatric surgeons.
• Pathologists.
• Pediatric radiation oncologists.
• Pediatric medical oncologists and hematologists.
• Ophthalmologists.
• Rehabilitation specialists.
• Pediatric oncology nurses.
• Social workers.
• Child-life professionals.
• Psychologists.
• Nutritionists.

For specific information about supportive care for children and adolescents with cancer, see the summaries on Supportive and Palliative Care.

The American Academy of Pediatrics has outlined guidelines for pediatric cancer centers and their role in the treatment of children and adolescents with cancer.[2] At these centers, clinical trials are available for most types of cancer that occur in children and adolescents, and the opportunity to participate 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 current standard therapy. Other types of clinical trials test novel therapies when there is no standard therapy for a cancer diagnosis. Most of the progress in identifying curative therapies 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 2020, childhood cancer mortality decreased by more than 50%.[3,4,5] Childhood and adolescent cancer survivors require close monitoring because side effects of cancer therapy may persist or develop months or years after treatment. For information about the incidence, type, and monitoring of late effects in childhood and adolescent cancer survivors, see Late Effects of Treatment for Childhood Cancer.

Childhood cancer is a rare disease, with about 15,000 cases diagnosed annually in the United States in individuals younger than 20 years.[6] The U.S. Rare Diseases Act of 2002 defines a rare disease as one that affects populations smaller than 200,000 people in the United States. Therefore, all pediatric cancers are considered rare.

The designation of a rare tumor is not uniform among pediatric and adult groups. In adults, rare cancers are defined as those with an annual incidence of fewer than six cases per 100,000 people. They account for up to 24% of all cancers diagnosed in the European Union and about 20% of all cancers diagnosed in the United States.[7,8] In children and adolescents, the designation of a rare tumor is not uniform among international groups, as follows:

• A consensus effort between the European Union Joint Action on Rare Cancers and the European Cooperative Study Group for Rare Pediatric Cancers estimated that 11% of all cancers in patients younger than 20 years could be categorized as very rare. This consensus group defined very rare cancers as those with annual incidences of fewer than two cases per 1 million people. However, three additional histologies (thyroid carcinoma, melanoma, and testicular cancer) with incidences of more than two cases per 1 million people were also included in the very rare group due to a lack of knowledge and expertise in the management of these tumors.[9]
• The Children's Oncology Group defines rare pediatric cancers as those listed in the International Classification of Childhood Cancer subgroup XI, which includes thyroid cancers, melanomas and nonmelanoma skin cancers, and multiple types of carcinomas (e.g., adrenocortical carcinomas, nasopharyngeal carcinomas, and most adult-type carcinomas such as breast cancers and colorectal cancers).[10] These diagnoses account for about 5% of the cancers diagnosed in children aged 0 to 14 years and about 27% of the cancers diagnosed in adolescents aged 15 to 19 years.[4]

  Most cancers in subgroup XI are either melanomas or thyroid cancers, with other cancer types accounting for only 2% of the cancers diagnosed in children aged 0 to 14 years and 9.3% of the cancers diagnosed in adolescents aged 15 to 19 years.

These rare cancers are extremely challenging to study because of the relatively few patients with any individual diagnosis, the predominance of rare cancers in the adolescent population, and the small number 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 Thymoma and Thymic Carcinoma Treatment.

References:

1. Smith MA, Seibel NL, Altekruse SF, et al.: Outcomes for children and adolescents with cancer: challenges for the twenty-first century. J Clin Oncol 28 (15): 2625-34, 2010.
2. American Academy of Pediatrics: Standards for pediatric cancer centers. Pediatrics 134 (2): 410-4, 2014. Also available online. Last accessed August 23, 2024.
3. Smith MA, Altekruse SF, Adamson PC, et al.: Declining childhood and adolescent cancer mortality. Cancer 120 (16): 2497-506, 2014.
4. National Cancer Institute: NCCR*Explorer: An interactive website for NCCR cancer statistics. Bethesda, MD: National Cancer Institute. Available online. Last accessed August 23, 2024.
5. Surveillance Research Program, National Cancer Institute: SEER*Explorer: An interactive website for SEER cancer statistics. Bethesda, MD: National Cancer Institute. Available online. Last accessed September 5, 2024.
6. Ward E, DeSantis C, Robbins A, et al.: Childhood and adolescent cancer statistics, 2014. CA Cancer J Clin 64 (2): 83-103, 2014 Mar-Apr.
7. Gatta G, Capocaccia R, Botta L, et al.: Burden and centralised treatment in Europe of rare tumours: results of RARECAREnet-a population-based study. Lancet Oncol 18 (8): 1022-1039, 2017.
8. DeSantis CE, Kramer JL, Jemal A: The burden of rare cancers in the United States. CA Cancer J Clin 67 (4): 261-272, 2017.
9. Ferrari A, Brecht IB, Gatta G, et al.: Defining and listing very rare cancers of paediatric age: consensus of the Joint Action on Rare Cancers in cooperation with the European Cooperative Study Group for Pediatric Rare Tumors. Eur J Cancer 110: 120-126, 2019.
10. Pappo AS, Krailo M, Chen Z, et al.: Infrequent tumor initiative of the Children's Oncology Group: initial lessons learned and their impact on future plans. J Clin Oncol 28 (33): 5011-6, 2010.

Latest Updates to This Summary (09 / 12 / 2024)

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.

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® Cancer Information for Health Professionals pages.

About This PDQ Summary

Purpose of This Summary

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

Reviewers and Updates

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).

Board members review recently published articles each month to determine whether an article should:

• be discussed at a meeting,
• be cited with text, or
• replace or update an existing article that is already cited.

Changes to the summaries are made through a consensus process in which Board members evaluate the strength of the evidence in the published articles and determine how the article should be included in the summary.

The lead reviewers for Childhood Thymoma and Thymic Carcinoma Treatment are:

• Denise Adams, MD (Children's Hospital Boston)
• Karen J. Marcus, MD, FACR (Dana-Farber Cancer Institute/Boston Children's Hospital)
• William H. Meyer, MD
• Paul A. Meyers, MD (Memorial Sloan-Kettering Cancer Center)
• Thomas A. Olson, MD (Aflac Cancer and Blood Disorders Center of Children's Healthcare of Atlanta - Egleston Campus)
• Alberto S. Pappo, MD (St. Jude Children's Research Hospital)
• Arthur Kim Ritchey, MD (Children's Hospital of Pittsburgh of UPMC)
• Carlos Rodriguez-Galindo, MD (St. Jude Children's Research Hospital)
• Stephen J. Shochat, MD (St. Jude Children's Research Hospital)

Any comments or questions about the summary content should be submitted to Cancer.gov through the NCI website's Email Us. Do not contact the individual Board Members with questions or comments about the summaries. Board members will not respond to individual inquiries.

Levels of Evidence

Some of the reference citations in this summary are accompanied by a level-of-evidence designation. These designations are intended to help readers assess the strength of the evidence supporting the use of specific interventions or approaches. The PDQ Pediatric Treatment Editorial Board uses a formal evidence ranking system in developing its level-of-evidence designations.

Permission to Use This Summary

PDQ is a registered trademark. Although the content of PDQ documents can be used freely as text, it cannot be identified as an NCI PDQ cancer information summary unless it is presented in its entirety and is regularly updated. However, an author would be permitted to write a sentence such as "NCI's PDQ cancer information summary about breast cancer prevention states the risks succinctly: [include excerpt from the summary]."

The preferred citation for this PDQ summary is:

PDQ® Pediatric Treatment Editorial Board. PDQ Childhood Thymoma and Thymic Carcinoma Treatment. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/types/thymoma/hp/child-thymoma-treatment-pdq. Accessed <MM/DD/YYYY>. [PMID: 31593390]

Images in this summary are used with permission of the author(s), artist, and/or publisher for use within the PDQ summaries only. Permission to use images outside the context of PDQ information must be obtained from the owner(s) and cannot be granted by the National Cancer Institute. Information about using the illustrations in this summary, along with many other cancer-related images, is available in Visuals Online, a collection of over 2,000 scientific images.

Disclaimer

Based on the strength of the available evidence, treatment options may be described as either "standard" or "under clinical evaluation." These classifications should not be used as a basis for insurance reimbursement determinations. More information on insurance coverage is available on Cancer.gov on the Managing Cancer Care page.

Contact Us

More information about contacting us or receiving help with the Cancer.gov website can be found on our Contact Us for Help page. Questions can also be submitted to Cancer.gov through the website's Email Us.

Last Revised: 2024-09-12