Thymic Cancer
Cancers of the thymus gland located in the chest. This guide explains types, myasthenia gravis connection, diagnosis, staging, surgery, chemotherapy, and radiation.
Quick Overview
Uncommon Cancer
Approximately 400-500 new cases annually in the United States. Less than 1% of all malignancies. [NCI, 2024]
Myasthenia Gravis Connection
30-50% of thymoma patients have myasthenia gravis. Conversely, 10-15% of MG patients have thymoma. [ACS, 2024]
Peak in 40-60 Years
Most common in middle age. Can occur at any age but very rare in children. [NCI, 2024]
Often Low-Grade
Thymomas are typically slow-growing. Thymic carcinomas are more aggressive. Grade affects treatment and prognosis. [NCCN, 2024]
What Is Thymic Cancer?
The thymus is a small gland in the chest behind the breastbone that produces T cells (immune cells). Thymic tumors include thymomas (arise from thymic epithelial cells, usually low-grade) and thymic carcinomas (more aggressive, worse prognosis). Thymomas can be associated with myasthenia gravis, an autoimmune condition causing muscle weakness. Many thymic tumors are discovered incidentally on chest imaging done for other reasons. [ACS, 2024]
Types & WHO Grading
Thymomas (WHO A, AB, B1, B2, B3)
Classified by WHO grading system. A/AB are most indolent. B3 more aggressive. Early stages have excellent prognosis; advanced stages require multimodal therapy. [NCI, 2024]
Thymic Carcinomas
More aggressive than thymomas. Include squamous, clear cell, mucinous types. Worse prognosis, require intensive multimodal therapy. Higher recurrence and mortality. [ACS, 2024]
Myasthenia Gravis Association
30-50% of thymoma patients develop MG. Can cause muscle weakness, eye drooping, difficulty breathing. MG usually improves with thymoma treatment. [NCI, 2024]
Other Autoimmune Conditions
Thymomas also associated with pure red cell aplasia, hypogammaglobulinemia, lupus. May improve with thymoma treatment. [ACS, 2024]
Diagnosis & Staging
Imaging: CT Chest
Often discovered incidentally on chest CT for other reasons. Shows mediastinal mass. [ACS, 2024]
Biopsy & Pathology
Tissue diagnosis obtained by biopsy or during surgical resection. WHO grading (for thymomas) or histology (for carcinomas) determined. [NCI, 2024]
Staging (Masaoka-Koga)
Stage I: confined to thymus. II: microscopic (IIa) or macroscopic (IIb) invasion. III: invasion of neighboring organs. IV: a) pleural/pericardial involvement, b) distant metastasis. [NCCN, 2024]
Myasthenia Gravis Screening
If symptoms suggest MG, testing for acetylcholine receptor antibodies or single fiber electromyography may confirm diagnosis. [ACS, 2024]
Treatment
Surgery (Thymectomy)
Mainstay of treatment for Stage I-II (sometimes III) thymomas. Complete resection offers best prognosis. Surgery alone may be curative for early stages. [NCCN, 2024]
Neoadjuvant Chemotherapy
For unresectable or advanced disease, preoperative chemotherapy can shrink tumor and improve resectability. Cisplatin-based regimens standard. [ACS, 2024]
Adjuvant Radiation
Used after surgery if complete resection not achieved or for invasive/advanced disease. May improve local control. [NCI, 2024]
Chemotherapy for Advanced Disease
Cisplatin-based combination chemotherapy for unresectable or metastatic disease. Multimodal approach (chemoradiation + surgery) for selected patients. [NCCN, 2024]
Management of Myasthenia Gravis
MG symptoms usually improve with thymoma treatment. Anticholinesterase drugs (pyridostigmine) manage symptoms. Immunosuppressive therapy if needed. [ACS, 2024]
Sources & References
- American Cancer Society (ACS). "Thymic Tumors." Cancer.org. Accessed 2024.
- National Cancer Institute (NCI). "Thymoma and Thymic Carcinoma Treatment (PDQ)." Cancer.gov. Accessed 2024.
- National Comprehensive Cancer Network (NCCN). "NCCN Guidelines: Thymoma and Thymic Carcinoma." Version 1.2024.
Last reviewed: February 2025. Not medical advice. Always consult your care team.