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