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