Radiation Oncology/Head & Neck/Sinonasal/Ethmoid sinuses

Ethmoid cancer

Risk factors

• Occupational
  • Sawdust, cement dust - ethmoid adenocarcinoma
  • Exposure to thoratrast, nickel, cadmium, formaldehyde
• Pollution
• Smoking
• HPV (SCC)
• ?chronic sinusitis

Pathology

• SCC most common
• Mucoepidermoid
• Adenoid cystic
• Adenocarcinoma
• Rare:
  • Olfactory neuroblastomas (esthesioneuroblastoma)
  • Angiosarcoma
  • Rhabdomyosarcoma
  • Lymphoma

Natural history

• Usually well differentiated, slow growing
• Present due to local invasion beyond sinus although can sometimes present due to sinusitis or nasal obstruction
• Tumours commonly invade through bone - through cribriform plate to anterior cranial fossa, or lamina papyracea to orbit

Route of spread

• Primarily through local invasion; nodal metastases are uncommon (< 20%, even lower for adenoid cystic)
• Nodal involvement is more common when there is extension into surrounding tissues
• Sinuses themselves are lymphatic poor
• First echelon lymph nodes are retropharyngeal

Presentation

• Facial or nasal pain
• Epistaxis
• Sinus obstruction
• Trismus (pterygoid involvement)
• Ocular symptoms: diplopia, visual disturbance, proptosis
• Neural involvement eg trigeminal neuralgia

Staging

See Staging

Outcomes

• Local control 50-60%
• Overall survival 30-50% at 5 years

Management

• Most evidence is via retrospective single institution reports
• Options:
  • Surgery (eg craniofacial resection, orbital exenteration)
    • Often difficult as locally advanced by the time of presentation
    • May include orbital exenteration if there is orbital invasion
  • Radiotherapy
    • Unclear whether preop or postop RT is better
      • Preop chemoRT may improve resectability
    • Adjuvant treatment does appear to increase local control although there exists no randomised data to confirm this
    • Radiotherapy as definitive management is most appropriate
      • Difficult resection anatomically
      • Dose 70Gy definitive, with chemotherapy for advanced lesions
      • Comprehensive nodal irradiation (retropharyngeal nodes) only if node positive or extrasinus involvement (skin, muscle)
      • Dose limiting structures
        • Eye, optic chiasm
        • Brain
      • Technique
        • Ant and wedged laterals (posterior to eye)
        • Treat neck nodes prophylactically if there is skin/muscle involvement otherwise target volume is antrum alone