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.

Posterior fossa giant adenoid cystic carcinoma with skull base invasion mimicking glomus jugulare: A case report and review of literature

“…The overall survival rate at 5 years is 75%, while the 10-years survival rate is 20% and the 15-years survival rate is approximately 10%. 5 The overall prognosis depends on a number of variables. Tubular, cribriform, and solid ACC are the three conventional categories, with the solid subtype having the worst prognosis.…”

Adenoid Cystic Carcinoma of the Nasopharynx with Skull Base Involvement: Retrospective National Cohort Analysis of Treatment Paradigms, Outcomes, and Provider Density

“…This study shows a 40% five-year survival rate for tumors invading the skull base, which is slightly lower than other studies which show an approximate 50 to 60% five-year survival. 2 3 6 A study by Ryckman et al examining the NACC in the National Cancer Database (NCDB) over a similar 10-year period showed that treatment was influenced by treating facility subtype and insurance status. The NCDB has an increased overall study population by increased population sample, but does not allow for geographic distribution analysis.…”

“…However, over the past two to three decades, this has increasingly been disproven and radiation is a mainstay of therapy. 1 2 6 8 9 10 The role of chemotherapy is overall unclear, as studies show conflicting data with regards to overall survival between patients receiving chemotherapy and radiation therapy alone. 3 6 This can be combined with surgical resection in individual cases due to a high rate of locoregional recurrence, but the overall indolent course of the tumor makes it difficult to recommend either radiation or surgery without consideration of the specific circumstances in each patient and the invasiveness of the tumor.…”

“…Adenoid cystic carcinoma of the nasopharynx (NACC) is relatively rare, accounting for less than 5% of head and neck adenoid cystic carcinomas (ACCs). 1 2 These tumors have traditionally been known for slow growth, distant metastases, and perineural invasion (PNI). The rate of NACC invading the skull base, despite the close proximity of the tumor to surrounding structures, is still less than 20%.…”

“…1 Those that do exist are generally single-institution studies that show that skull base involvement, recurrence, perineural, or lymphovascular spread can lead to decreased survival, as would be expected. 2 3 Determining survival outcomes has been very limited given the rarity of these tumors, their relative slow growth, and slow onset of symptoms. In this study, we retrospectively analyzed survival outcomes and treatment paradigms for a national cohort of patients with NACC.…”