Abstract

6102 Background: Adenoid cystic carcinoma (ACC) is a rare salivary gland malignancy with a paucity of clinical outcome data. As such, evidence supporting and informing current guidelines remains limited. Methods: Inclusion criteria stipulated adults with adenoid cystic carcinoma treated at the University of Michigan between 1988 and 2019 with complete records (n=102). Clinical variables including demographics, disease stage, and treatment modality were abstracted. Pathologic variables analyzed included tumor grade, perineural invasion, lymphovascular invasion, and surgical margin status. Multivariate analyses were performed with disease recurrence calculated with Kaplan-Meier methodology as the primary outcome. Results: Mean age at diagnosis was 59 years; stage I and II disease accounted for 35 (38%) patients. Initial treatment was most commonly surgery with adjuvant radiation (77%). Median follow-up was 3 years. Distant metastatic disease developed in 34 (33%) patients. Most common sites included lung (68%), bone (21%), and brain (21%). Median time to distant metastases was 46 months with median overall survival of 58 months. Patients with locoregional recurrence experienced median survival of 91 months. Multivariate analysis adjusted for grade, perineural invasion, and surgical margin status (Table). Grade 3 tumors with predominantly solid histologic pattern pose higher risk of recurrence compared to grade 1 tubular histologic patterns as a reference (HR 3.69, 95% CI 1.15-11.88, p=0.028). Conclusions: Survival among patients with adenoid cystic carcinoma after locoregional recurrence is significantly better compared to those experiencing distant metastasis. Furthermore, tumor grade is most predictive of recurrence. Additionally, distant metastases may emerge over the course of many years. These data from one of the largest retrospective databases to date may inform the development of disease-specific surveillance guidelines and novel salvage treatment paradigms. [Table: see text]