Parotid Gland Salivary Malignancies: Characterizing Outcomes Based on Facial Nerve Involvement

Presentation: P758
Topic: Salivary Gland
Type: Poster
Date:
Session:
Authors: Khashayar Arianpour, MD1; Bryan Hair, BA2; Meghan Crawley, MD1; Shlomo A Koyfman, MD3; Brian B Burkey, MD1; Eric D Lamarre, MD1
Institution(s): 1Head and Neck Institute – Cleveland Clinic; 2Cleveland Clinic Lerner College of Medicine of Case Western Reserve University; 3Department of Radiation Oncology, Taussig Cancer Institute, Cleveland Clinic


Importance

: Salivary gland malignancies involving the parotid gland may abut, microscopically invade, or grossly invade the facial nerve. This, in turn, dictates intraoperative approach to managing the facial nerve. Our general approach is to maintain the nerve intact if functioning preoperatively and if not grossly involved intraoperatively.  Clinical outcomes in parotid gland malignancies with respect to extent of facial nerve involvement is not well characterized in the current literature. 


Objective

: Investigate outcomes in salivary gland malignancies of the parotid gland as they pertain to extent of facial nerve involvement and factors associated with survival.


Design, Setting and Participants

: Retrospective cohort study of adults at a tertiary care center who underwent superficial or total parotidectomy for salivary gland malignancy of the parotid gland.


Main Outcome(s) and Measure(s)

: Disease-specific survival (DSS) and disease-free survival (DFS) of parotid salivary gland malignancies were evaluated using Kaplan-Meier analysis with log-rank testing, specifically comparing tumors that are peeled off the facial nerve, versus those demonstrating neural invasion thereby requiring partial or complete sacrifice.


Results

: A total 333 patients (41.4% without CNVII involvement, 26.7% abutting but peeled off, 31.8% partial or complete sacrifice) with median age 59.6 years, were followed for a median of 47.9 months. Tumors were histologically graded in 326 patients (low 45.1%, intermediate 11.7% or high 43.3%). Most common malignancies were mucoepidermoid carcinoma (n=78), salivary duct carcinoma (n=48) and acinic cell carcinoma (n=45). The three categories of facial nerve involvement (none, peel-off and sacrifice) were different in both DSS and DFS (p < 0.0001). DSS at 5 years was 94.7%, 86.6% and 69.5% when there was no facial nerve involvement, the tumor was peeled off the nerve and when the nerve was sacrificed, respectively. DFS at 5 years was 87.2%, 80.1% and 49.9% for those respective groups. High-grade subgroup analysis revealed that overall DSS did not differ in tumors that were peeled off the nerve compared to tumors that required partial or complete nerve sacrifice (p = 0.5531). The DSS and DFS at 5 years in the high-grade subgroup were 91.4%, 65.0%, 59.6% and 81.1%, 66.1% and 42.6%, respectively.


Conclusion and Relevance

: Our large cohort confirms that the extent of facial nerve involvement in salivary gland malignancies of the parotid gland impact both overall and 5-year DSS and DFS. However, in the high-grade subgroup, peeling the tumor provides no improved survival outcomes compared to facial nerve sacrifice.