Seventeen patients (13 men, 4 women) with unresectable carcinomas of the NCPS who underwent PBT at the University of Tsukuba between 2001 and 2007 were analyzed. The patients' median age was 62 years (range, 30-83 years). The tumors were located in the nasal cavity in 3 patients, the frontal sinus in 1, the ethmoid sinus in 9, and the maxillary sinus in 4. The clinical stage was Stage IVA in 5 cases, IVB in 10, and recurrent in 2. The tumors were deemed unresectable for medical reasons in 16 patients and because of refusal at a previous hospital 4 months earlier in 1 patient. All the patients received PBT irradiation dose of 22-82.5 GyE and a total of 72.4-89.6 GyE over 30-64 fractions (median 78 GyE over 36 fractions) with X-ray, with attention not exceeding the delivery of 50 GyE to the optic chiasm and brainstem.
The overall survival rate was 47.1 % at 2 years and 15.7 % at 5 years, and the local control rate was 35.0 % at 2 years and 17.5 % at 5 years. Invasion of the frontal or sphenoid sinus was a prognostic factor for overall survival or local control. Late toxicity of more than Grade 3 was found in 2 patients (brain necrosis in 1 and ipsilateral blindness in 1); however, no mortal adverse effects were observed.
Proton beam therapy enabled a reduced irradiation dose to the optic chiasm and brainstem, enabling the safe treatment of unresectable carcinomas in the NCPS. Superior or posterior extension of the tumor influenced patient outcome.