Skull Base 2008; 18 - A110
DOI: 10.1055/s-2008-1093198

Proton Beam Therapy for Unresectable Adenoid Cystic Carcinoma of the Skull Base

Annie W Chan 1(presenter), Paul M Busse 1, Urmila R Kamat 1, Derrick T Lin 1, Norbert B Liebsch 1
  • 1Boston, USA

Introduction: To determine the treatment outcome and toxicity in patients with unresectable adenoid cystic carcinoma with skull base involvement treated with proton beam therapy.

Methods: Between 1991 and 2006, 16 patients with unresectable T4 adenoid cystic carcinoma with skull base extension were treated with proton beam therapy at our institutions. The median age was 48 years. The primary tumor location included the maxillary sinus in two, nasal cavity in one, sphenoid sinus in five, nasopharynx in six, and hard palate in two patients. All the patients underwent biopsy only and received definitive proton beam therapy. The median total radiation dose to the primary tumor was 76 Gy. Thirty-one percent of patients received weekly concurrent cisplatin.

Results: With a median follow-up of 37 months for all living patients, there was no local or regional recurrence. The rate of freedom from distant metastasis at 2 years was 75%. The disease-free and overall survival rates at 2 years were 75% and 80%, respectively. None of the patients underwent orbital exenteration after radiation. None of the patients developed any grade 5 ocular or visual complication. Six patients developed grade 3 or higher neurologic late effects.

Conclusions: High-dose proton beam therapy results in a very encouraging local control rate in patients with unresectable adenoid cystic carcinoma of the skull base. Longer follow-up will be required to determine if our high local control rates are durable.