What is the recommended treatment for adenoid cystic carcinoma (ACC) of the nasal septum?

Treatment of Adenoid Cystic Carcinoma of the Nasal Septum

Radical surgical resection followed by postoperative radiation therapy is the optimal treatment for adenoid cystic carcinoma (ACC) of the nasal septum, offering the best outcomes for morbidity, mortality, and quality of life. 1

Primary Treatment Approach

Surgical Management

• Complete surgical resection with negative margins is the cornerstone of treatment
• Surgical approach should be determined based on tumor extent:
  • Endoscopic endonasal approach for selected cases (reduces morbidity while maintaining oncological outcomes) 2
  • Combined approaches (cranial, endoscopic, transpalatal) for tumors with extensive invasion 3
• Ipsilateral neck dissection should be performed for T3-T4 tumors 1

Radiation Therapy

• Postoperative radiation therapy should be offered to all patients with resected ACC, regardless of stage 1
• Recommended dose: 60-70 Gy in standard fractions 1
• Target volume should include:
  • Surgical bed
  • Appropriate nodal levels
  • Associated nerve pathways to skull base if perineural invasion is present 1
• Intensity-modulated radiation therapy (IMRT) is preferred for better local tumor control and reduced toxicity 1

Prognostic Factors and Treatment Considerations

Negative Prognostic Factors

• High T-stage disease
• Grade III histology
• Positive surgical margins
• Perineural infiltration 2
• High Ki-67 expression (associated with treatment failure and wide topical spread) 4

Treatment Outcomes

• 5-year overall survival rates range from 62.9% to 86.5% 5, 2
• Local recurrence rates: 30% 5
• Distant metastasis rates: 38% 5

Management of Recurrence and Advanced Disease

Local Recurrence

• Revision surgery when feasible
• Consider additional radiation therapy options:
  • Brachytherapy
  • Stereotactic radiotherapy
  • Intensity-modulated radiotherapy 1

Metastatic Disease

• For limited metastases (≤5): Consider local ablative treatments (surgery or stereotactic body radiation therapy) 1
• Conventional chemotherapy has limited efficacy for metastatic disease 1
• Clinical trials should be considered when available 1

Follow-up and Surveillance

• Regular clinical examinations of the nasopharynx and neck
• Evaluation of cranial nerve function
• Imaging surveillance:
  • Initial post-treatment imaging at 3 months
  • Yearly imaging for at least 2 years
  • Extended surveillance beyond 5 years due to late recurrences
• Chest CT yearly for at least 2 years (standard chest X-ray lacks sensitivity) 1

Common Pitfalls and Caveats

1. Inadequate Margins: ACC has a propensity for perineural invasion and submucosal spread, making complete resection challenging. Intraoperative frozen sections should be used to ensure negative margins.

2. Insufficient Follow-up: ACC has a high rate of late recurrences and distant metastases, necessitating long-term surveillance beyond the standard 5-year period 3.

3. Underestimating Perineural Spread: Radiation fields must include neural pathways to the skull base when perineural invasion is present 1.

4. Overlooking Distant Metastases: Despite metastatic disease, 10% of patients with ACC can survive more than 10 years, emphasizing the importance of comprehensive staging and surveillance 1.