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Cancer Health Center

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Thymoma and Thymic Carcinoma Treatment (PDQ®): Treatment - Health Professional Information [NCI] - Stage Information for Thymoma and Thymic Carcinomas

Thymoma Staging System of Masaoka 1994a

IMacroscopically, completely encapsulated; microscopically, no capsular invasion.
IIMacroscopic invasion into surrounding fatty tissue or mediastinal pleura; microscopic invasion into capsule.
IIIMacroscopic invasion into neighboring organs (pericardium, lung, and great vessels).
IVaPleural or pericardial dissemination.
IVbLymphogenous or hematogenous metastases.

Application of this staging system to a series of 85 surgically treated patients confirmed its value in determining prognosis, with 5-year survival rates of 96% for stage I disease, 86% for stage II disease, 69% for stage III disease, and 50% for stage IV disease.[11,13] In a large, retrospective study involving 273 patients with thymoma, 20-year survival rates (as defined by freedom from tumor death) according to the Masaoka staging system were reported to be 89% for stage I disease, 91% for stage II disease, 49% for stage III disease, and 0% for stage IV disease.[9]

In a retrospective analysis of 130 resected, thymoma patients, the WHO pathological classification was tightly correlated with stage and by multivariate analysis, tumor size, completeness of resection, histologic subtype, and stage were significant prognostic factors for survival. Of note, only four patients received neoadjuvant cisplatin-based chemotherapy and complete resection was possible in 95% of cases. The 5-year survival rate of the 11 stage IV patients was 47%.[12]

Some investigators maintain that the Masaoka staging system does not accurately predict outcome for thymic carcinoma.[14,15] In one retrospective study evaluating 43 cases of thymic carcinoma, prognosis was found to be dependent solely on tumor invasion of the innominate artery.[15]


  1. Sperling B, Marschall J, Kennedy R, et al.: Thymoma: a review of the clinical and pathological findings in 65 cases. Can J Surg 46 (1): 37-42, 2003.
  2. Rendina EA, Venuta F, Ceroni L, et al.: Computed tomographic staging of anterior mediastinal neoplasms. Thorax 43 (6): 441-5, 1988.
  3. Rosai J: Histological Typing of Tumours of the Thymus. New York, NY: Springer-Verlag, 2nd ed., 1999.
  4. Tomiyama N, Johkoh T, Mihara N, et al.: Using the World Health Organization Classification of thymic epithelial neoplasms to describe CT findings. AJR Am J Roentgenol 179 (4): 881-6, 2002.
  5. Sasaki M, Kuwabara Y, Ichiya Y, et al.: Differential diagnosis of thymic tumors using a combination of 11C-methionine PET and FDG PET. J Nucl Med 40 (10): 1595-601, 1999.
  6. Kageyama M, Seto H, Shimizu M, et al.: Thallium-201 single photon emission computed tomography in the evaluation of thymic carcinoma. Radiat Med 12 (5): 237-9, 1994 Sep-Oct.
  7. Adams S, Baum RP, Hertel A, et al.: Metabolic (PET) and receptor (SPET) imaging of well- and less well-differentiated tumours: comparison with the expression of the Ki-67 antigen. Nucl Med Commun 19 (7): 641-7, 1998.
  8. Kubota K, Yamada S, Kondo T, et al.: PET imaging of primary mediastinal tumours. Br J Cancer 73 (7): 882-6, 1996.
  9. Okumura M, Ohta M, Tateyama H, et al.: The World Health Organization histologic classification system reflects the oncologic behavior of thymoma: a clinical study of 273 patients. Cancer 94 (3): 624-32, 2002.
  10. Chen G, Marx A, Wen-Hu C, et al.: New WHO histologic classification predicts prognosis of thymic epithelial tumors: a clinicopathologic study of 200 thymoma cases from China. Cancer 95 (2): 420-9, 2002.
  11. Masaoka A, Monden Y, Nakahara K, et al.: Follow-up study of thymomas with special reference to their clinical stages. Cancer 48 (11): 2485-92, 1981.
  12. Nakagawa K, Asamura H, Matsuno Y, et al.: Thymoma: a clinicopathologic study based on the new World Health Organization classification. J Thorac Cardiovasc Surg 126 (4): 1134-40, 2003.
  13. Cameron RB, Loehrer PJ Sr, Thomas CR Jr: Neoplasms of the mediastinum. In: DeVita VT Jr, Hellman S, Rosenberg SA, eds.: Cancer: Principles and Practice of Oncology. 7th ed. Philadelphia, Pa: Lippincott Williams & Wilkins, 2005, pp 845-58.
  14. Ritter JH, Wick MR: Primary carcinomas of the thymus gland. Semin Diagn Pathol 16 (1): 18-31, 1999.
  15. Blumberg D, Burt ME, Bains MS, et al.: Thymic carcinoma: current staging does not predict prognosis. J Thorac Cardiovasc Surg 115 (2): 303-8; discussion 308-9, 1998.

This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http:// cancer .gov or call 1-800-4-CANCER.

WebMD Public Information from the National Cancer Institute

Last Updated: May 28, 2015
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.
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