What is the management approach for thymoma?

Thymoma Management

Complete surgical resection via open median sternotomy is the cornerstone of thymoma treatment for all resectable disease, with adjuvant therapy determined by stage and resection completeness. 1

Stage-Based Treatment Algorithm

Stage I Disease

• Perform complete surgical resection through open median sternotomy, removing the entire thymus from phrenic nerve to phrenic nerve laterally and from diaphragm to thyroid gland superiorly. 1
• Do not use adjuvant radiotherapy or chemotherapy after complete resection. 1
• Minimally invasive approaches (VATS) are not standard of care and should be avoided. 1
• For medically inoperable patients, use chemoradiation or radiation alone. 1

Stage II Disease

• Complete surgical resection via open median sternotomy remains the standard approach. 1
• For Stage IIA with complete resection: Do not routinely use adjuvant radiation. 1
• For Stage IIB or high-risk features (capsular invasion, close margins, WHO grade B histology, pericardial adherence): Add adjuvant radiation therapy. 1
• Counsel younger patients about long-term radiation risks including secondary malignancies and coronary artery disease. 1
• Do not use adjuvant chemotherapy. 1
• For medically inoperable patients, use chemoradiation or radiation alone. 1

Stage III Disease

• Evaluate all patients for multimodality therapy combining neoadjuvant chemotherapy, surgical resection, and adjuvant chemoradiotherapy. 1

Surgical Approach for Stage III:

• For Stage IIIA: Proceed directly to surgery if complete resection appears feasible, or use neoadjuvant therapy first. 1
• For Stage IIIB: Administer neoadjuvant chemoradiotherapy before attempting surgical resection. 1
• If complete resection is impossible at thoracotomy, perform maximal debulking with vascular reconstruction and place surgical clips to mark residual tumor for radiation targeting. 1
• Never resect both phrenic nerves due to severe respiratory morbidity. 1

Neoadjuvant Therapy for Stage III:

• Obtain tissue diagnosis via CT-guided core-needle biopsy or open surgical biopsy before starting neoadjuvant therapy. 1
• Use cisplatin-based combination chemotherapy (cisplatin plus anthracycline regimens have the most clinical experience). 1
• For small treatment volumes: Use concurrent chemoradiotherapy. 1
• For bulky tumors: Use sequential therapy with chemotherapy followed by radiation, then surgery. 1

Adjuvant Therapy for Stage III:

• Administer adjuvant radiotherapy after resection. 1
• Consider adjuvant chemotherapy, though insufficient data exists to routinely recommend it after complete resection. 1

Unresectable Stage III:

• Use chemotherapy concurrent with or sequential to radiation therapy when surgery is inappropriate. 1
• Unresectable disease is defined as extensive tumor involving trachea, great arteries, and/or heart that has not responded to cisplatin-based chemotherapy. 1

Stage IVA Disease

• Apply Stage III recommendations with modifications for pleural/pericardial metastases. 1
• Perform surgery only if all pleural and pericardial metastases can be completely resected. 1
• Use neoadjuvant chemoradiotherapy with cisplatin-based regimens. 1
• Consider adjuvant chemoradiotherapy after resection. 1
• For unresectable disease: Use chemotherapy (cisplatin plus anthracycline-containing regimens) with or without radiation. 1
• Patients often respond to multiple sequential single-agent therapies after first-line progression. 1

Critical Diagnostic Considerations

When Lymphadenopathy is Present:

• Do not assume thymoma diagnosis when multiple lymphadenopathies accompany an anterior mediastinal mass—this presentation strongly suggests alternative diagnoses. 2
• Urgently exclude lymphoma, thymic carcinoma, and germ cell tumors before proceeding with thymoma-directed therapy. 2
• Measure AFP and β-hCG levels in teenagers and young adults to exclude germ cell tumors. 2
• Obtain tissue confirmation via core needle biopsy (not fine-needle aspiration) to allow histologic, immunohistochemical, and molecular analyses. 2
• Avoid transpleural biopsy approaches for possible thymoma. 2

Surgical Technical Standards

• Use open median sternotomy as the standard surgical approach for all stages. 1
• Minimally invasive approaches lack sufficient evidence and should not be used as standard care, though some expert centers report safety in highly selected early-stage cases. 1, 3, 4
• Remove the entire thymus including perithymic fat from phrenic nerve to phrenic nerve and diaphragm to thyroid gland. 1
• Preserve at least one phrenic nerve to avoid severe respiratory morbidity. 1

Radiation Therapy Specifications

• Limit total cardiac dose to ≤30 Gy given younger patient age and long survival expectations. 2
• Deliver 45-70 Gy to the primary tumor bed depending on margin status. 2
• Do not perform extensive elective nodal radiation, as true thymomas do not typically metastasize to lymph nodes. 2

Perioperative Myasthenia Gravis Management

• Screen all patients for myasthenia gravis before any surgical procedure, even if asymptomatic, to prevent perioperative respiratory failure. 2
• Myasthenia gravis does not confer adverse prognosis and may indicate earlier stage disease. 5

Surveillance Protocol

• Perform chest CT with contrast every 6 months for 2 years, then annually until 10 years to monitor for late recurrences. 2
• Treat recurrences similarly to newly diagnosed advanced disease with surgery or radiation if locoregional and clinically feasible. 2

Common Pitfalls to Avoid

• Do not use minimally invasive surgery as standard approach despite emerging reports—open sternotomy remains the evidence-based standard. 1
• Do not give routine adjuvant radiation for completely resected Stage I or IIA disease. 1
• Do not assume thymoma when lymphadenopathy is present—obtain tissue diagnosis first. 2
• Do not resect both phrenic nerves even for complete tumor clearance. 1
• Do not proceed with neoadjuvant therapy without tissue confirmation. 1
• Do not exceed 30 Gy cardiac dose during radiation therapy. 2