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Original Investigation
May 2016

A 20-Year Review of 75 Cases of Salivary Duct Carcinoma

Author Affiliations
  • 1Department of Otolaryngology–Head and Neck Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania
  • 2Division of Otolaryngology–Head and Neck Surgery, Department of Surgery, Southern Illinois University, Springfield
  • 3Department of Otolaryngology–Head and Neck Surgery, The Johns Hopkins University, Baltimore, Maryland
JAMA Otolaryngol Head Neck Surg. 2016;142(5):489-495. doi:10.1001/jamaoto.2015.3930

Importance  Salivary duct carcinoma is a rare, aggressive malignancy of the salivary glands. Owing to its rare nature, clinical data are limited, and only a few clinical studies comprise more than 50 patients.

Objective  To review the University of Pittsburgh Medical Center’s experience with salivary duct carcinoma over a 20-year period, focusing on demographics, presentation, treatment, and outcome.

Design, Setting, and Participants  This investigation was a retrospective cohort study in a multihospital institution with tertiary referral. A pathology database was reviewed for all cases of histopathologically diagnosed salivary duct carcinoma from January 1, 1995, to October 20, 2014. Patients who were referrals for pathology review only and were never seen at the institution were excluded. In total, 75 study patients were identified. The electronic medical record was reviewed for details regarding demographics, presentation, treatment, and outcome, including overall survival (OS) and disease-free survival (DFS). This study was supplemented with a review of the institution’s Head and Neck Oncology Database for further clinical details.

Main Outcomes and Measures  Primary outcome measures consisted of OS and DFS.

Results  The study sample comprised 75 participants with a mean age at diagnosis of 66.0 years (age range, 33-93 years), and 29% (n = 22) were female. Most primary tumors were from the parotid gland (83%), with the next most frequent site being the submandibular gland (12%). Overall, 41% of the cases were carcinoma ex pleomorphic adenoma. Rates of other histologic features included the following: perineural invasion (69%), extracapsular spread (58%), ERBB2 (formerly HER2) positivity (31%) (62% of those who were tested), and vascular invasion (61%). The median OS was 3.1 years, and the median DFS was 2.7 years. Univariate Kaplan-Meier survival analyses demonstrated that facial nerve sacrifice and extracapsular spread were associated with lower OS (2.38 vs 5.11 years and 2.29 vs 6.56 years, respectively) and DFS (2.4 vs 3.88 years and 1.44 vs 4.5 years, respectively). Although underpowered, multivariable analysis demonstrated significantly worse OS in patients with N2 and N3 disease (hazard ratio [HR] 8.42, 95% CI, 1.84-38.5) but did not show significantly worse DFS or OS for facial nerve sacrifice or extracapsular spread. There was no association between ERBB2 positivity and survival and no difference in survival between patients receiving radiation therapy vs radiation therapy plus chemotherapy. No patients had recurrence or distant metastasis after 5 disease-free years.

Conclusions and Relevance  Salivary duct carcinoma is an aggressive disease. A large number of cases in this review were carcinoma ex pleomorphic adenoma and had classic negative prognostic indicators, such as perineural invasion, vascular invasion, and extracapsular spread. ERBB2 positivity was not associated with any difference in survival. Facial nerve involvement appears to indicate worse prognosis, as does nodal stage higher than N1. Recurrence and metastasis after 5 years are rare.