Impact of Radiation Therapy Volumes on Skull Base Recurrence in Adenoid Cystic Carcinoma in the Head and Neck

Abstract Objectives This article examines a national cohort of patients with nasopharyngeal adenoid cystic carcinoma (ACC) for incidence, skull base invasion, overall survival, and treatment paradigms. Design, Setting, and Participants Retrospective national population-based study using Surveillance, Epidemiology, and End Results program data of patients with ACC of the nasopharynx (NACC) and skull base between 2004 and 2016. Main Outcomes and Measures Primary outcomes included 5-year overall survival and odds of radiation treatment. Statistical analysis was performed using STATA 15.0 (STATACorp). p-Values < 0.05 were considered statistically significant. Results Of the 2,385 cases of ACC, 70 cases were classified as NACC. Twenty-one percent (15) involved invasion of the skull base or posterior pharyngeal wall, and 42% (30) were either stage 3 or stage 4. The 5-year overall survival for patients with NACC without skull base invasion was 67% which dropped to 40% with invasion into the skull base. Radiation was used as the primary form of therapy for 62% of NACC and 73% of NACC invading into skull base. Odds of receiving radiation therapy and 5-year survival were not affected by socioeconomic status or density of providers. Conclusion NACC is rare in incidence and was most commonly treated with radiation therapy when advanced in stage. Prognosis was dependent on invasion through posterior pharyngeal wall and skull base. Provider density and socioeconomic status did not affect odds of radiation or overall survival for NACC.

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Adenoid Cystic Carcinoma of the Skull Base: Response to Radiation Therapy and Outcomes in a Retrospective Case Series

Journal of Neurological Surgery Part B Skull Base ◽

10.1055/s-0039-1696706 ◽

2019 ◽

Vol 81 (05) ◽

pp. 505-510 ◽

Cited By ~ 1

Author(s):

Shekhar K. Gadkaree ◽

Anuraag S. Parikh ◽

Alejandro I. Rodarte ◽

Ashton Lehmann ◽

Stacey T. Gray ◽

...

Keyword(s):

Overall Survival ◽

Radiation Therapy ◽

Adenoid Cystic Carcinoma ◽

Skull Base ◽

Proton Beam ◽

Locoregional Control ◽

Single Center ◽

Beam Radiation ◽

Adenoid Cystic ◽

Pathologic Features

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.

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