Treatment of Myoepithelial Cancer of the Tonsil
Myoepithelial carcinoma of the tonsil should be treated with complete surgical resection followed by adjuvant radiotherapy, with consideration of chemotherapy for high-grade tumors or adverse pathologic features.
Primary Treatment Approach
Surgery is the cornerstone of treatment for myoepithelial carcinoma of the tonsil. The goal is complete resection with wide surgical margins, as this rare malignancy demonstrates high rates of local recurrence and metastatic spread 1. For tonsillar location specifically, surgical excision should include ipsilateral or bilateral neck dissection depending on tumor characteristics 2.
- Complete surgical resection with wide margins is essential, as marginal resections are associated with significantly higher recurrence rates (100% vs 35.7% for wide margins in myoepithelial carcinoma of soft tissue and bone) 1
- Bilateral neck dissection should be strongly considered given the tonsillar location and the 50-60% rate of occult neck metastases typical of anterior oropharyngeal cancers 2
- Intraoperative margin assessment is critical—if clear resection margins appear uncertain, surgical clips should be placed to guide postoperative radiotherapy 3
Adjuvant Radiotherapy
Adjuvant radiotherapy significantly improves survival in high-grade myoepithelial carcinoma and should be administered postoperatively. Analysis of SEER registry data demonstrated improved overall survival with adjuvant radiation therapy in patients with grade III or IV myoepithelial carcinoma (p<0.01) 4.
- Radiation should be delivered to 5580-6600 cGy in 180-200 cGy fractions to the surgical bed with a 2 cm margin 4, 3
- Treatment should begin within 6 weeks of surgery, as delays beyond this timeframe negatively impact outcomes 2
- Dose escalation to 60-66 Gy is recommended for regions with microscopically positive margins or other adverse features 3
Role of Chemotherapy
Chemotherapy should be considered as part of multimodality treatment, particularly for high-grade tumors or metastatic disease. While myoepithelial carcinoma shows chemosensitivity, responses are typically short-lived 1.
- Cisplatin plus doxorubicin is the most studied first-line regimen, achieving objective responses in 5 of 6 patients (83%) with metastatic myoepithelial carcinoma, though median response duration was only 4 months 1
- Ifosfamide-based regimens (ifosfamide, cisplatin, and etoposide) have been used successfully in pediatric cases 4
- Concurrent chemoradiotherapy with high-dose cisplatin (100 mg/m² every 3 weeks) is preferred when adverse pathologic features are present, such as extracapsular nodal spread or positive margins 2
Treatment Algorithm by Disease Extent
Localized Disease
- Complete surgical resection with wide margins and neck dissection 1, 2
- Adjuvant radiotherapy (5580-6600 cGy) starting within 6 weeks of surgery 4, 2
- Consider concurrent chemotherapy if high-grade features, positive margins, or extracapsular extension present 2, 1
Metastatic Disease at Presentation
- Multimodality treatment is mandatory 1
- Neoadjuvant chemotherapy (cisplatin/doxorubicin) may be considered to reduce tumor burden 1
- Surgery if resectable after chemotherapy, followed by radiotherapy 1
- Five-year overall survival is only 12.5% for patients metastatic at diagnosis, compared to 62.6% for localized disease 1
Critical Pitfalls to Avoid
Do not perform marginal resections—the single patient with marginal resection in the largest myoepithelial carcinoma series experienced recurrence, compared to 35.7% recurrence with wide margins 1.
Do not delay adjuvant therapy beyond 6 weeks postoperatively, as this significantly worsens outcomes 2.
Do not rely on chemotherapy alone for localized disease—despite objective responses, median duration is only 4 months and outcomes remain poor without surgical resection 1.
Do not underestimate the metastatic potential—60% of patients with localized myoepithelial carcinoma at diagnosis subsequently developed metastases 1.
Multidisciplinary Management
Treatment decisions must be made by a multidisciplinary team including head and neck surgery, radiation oncology, and medical oncology, given the rarity of this malignancy and absence of standardized protocols 1. Referral to centers with expertise in rare head and neck malignancies is strongly encouraged 1.