High-Grade Salivary Duct Carcinoma of the Parotid Gland: Clinicopathologic Features and Treatment Outcomes

Objectives: (1) Analyze the treatment approach for these rare salivary gland neoplasms at our institution. (2) Demonstrate observed patterns of failure and survival for high-grade salivary duct carcinoma (HGSDC) involving the parotid glands. Methods: Clinical data on 17 patients with nonmetastatic HGSDC involving parotid salivary glands from 1998 to 2012 were abstracted from our institutional database. Inclusion required surgical resection with postoperative radiotherapy (n = 8) or concurrent chemoradiotherapy (n = 9). Demographics, histopathologic features, treatment course, and clinical outcomes were recorded. Specimens were re-reviewed by a dedicated head and neck pathologist. Overall survival (OS) and disease-free survival (DFS) were estimated via Kaplan-Meier method, and comparisons were made with the log-rank test. Results: Median patient age was 65 years (range, 52-83 years) with a male:female ratio of 7.5:1 and median follow-up of 37 months. Most commonly, these cases presented as pT4a (n = 14) with adverse clinical features, including perineural invasion (76.5%), positive lymph nodes (76.5%), and vascular invasion (58.8%). Three-year DFS and OS were 35.7% and 61.4%, respectively. The pattern of treatment failure was predominately distant (n = 11) versus locoregional (n = 3). Univariate analysis of demographic, histopathologic, and treatment characteristics did not reveal a significant association with OS or DFS. Median survival after metastasis was 13 months, with only a single patient having a sustained treatment response >2 years after disease dissemination. Conclusions: In this series, we highlight the aggressive nature of high-grade salivary duct carcinoma, which has a significant risk of distant recurrence and poor overall survival.