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DOI: 10.1055/s-0039-1696706
Adenoid Cystic Carcinoma of the Skull Base: Response to Radiation Therapy and Outcomes in a Retrospective Case Series
Abstract
Objectives The main purpose of this article is to examine a single-center cohort of patients with nasopharyngeal adenoid cystic carcinoma (ACC) for pathologic features, skull base invasion, overall survival, and disease-free survival, with a focus on response to proton beam radiation therapy.
Design, Setting, and Participants Single-center institutional cancer registry was used to retrospectively identify and analyze outcomes for 12 patients treated for ACC of the nasopharynx from 2000 to 2016.
Main Outcomes and Measures Primary outcomes included 5-year overall survival and locoregional control. Statistical analysis was performed using STATA 12.0 (STATACorp, College Station, Texas, United States). Spearman's rank order correlation was used for ordinal, monotonic variables with p-values <0.05 considered statistically significant. Survival analysis was performed by Kaplan–Meier method; comparison between groups was performed using log-rank test.
Results Twelve patients with ACC of the nasopharynx were included. All patients presented with advanced disease and were treated with primary radiation therapy, typically proton beam therapy. Only two underwent a surgical attempt at resection. A majority of cases had a cribriform growth pattern. The 5-year survival was 75% and rate of locoregional control rate at 5 years was 50%, comparable to other ACC cohort studies that included earlier stage tumors in various subsites that were surgically resected.
Conclusions Although ACC is traditionally noted to be radioresistant, ACC of the nasopharynx was responsive to radiotherapy in our cohort, despite advanced stage and skull base invasion. Reasons for this improved survival are unclear and suggest the need for further pathologic and genetic characterization of nasopharyngeal ACC.
Keywords
nasopharyngeal malignancy - adenoid cystic carcinoma - skull base - radiation therapy - outcomesGeneral Disclosures
The authors have not received financial assistance related to this manuscript.
Funding/supporting organizations had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; or decision to submit the manuscript for publication.
These results of this study were presented at the North American Skull Base Society Annual Meeting in February, 2019 in Orlando, FL.
Publication History
Received: 04 April 2019
Accepted: 28 July 2019
Article published online:
18 September 2019
Georg Thieme Verlag KG
Stuttgart · New York