Practice Patterns in Management of Low- to Intermediate-Grade Salivary Gland Carcinoma: A Multi-Institutional Study

To characterize practice patterns and outcomes in the management of low- and intermediate-grade salivary gland carcinoma prior to the existence of treatment guidelines.

Analysis of a registry of patients who underwent parotid and submandibular gland resections for low-and intermediate-grade carcinomas between 2010 and 2019.

Of all 786 patients included in the study, 726 (92%) had preoperative imaging and 653 (83%) had preoperative biopsy. Of the 729 patients with parotid gland cancer, the majority underwent superficial (n = 384, 53%) or total (n = 254, 35%) parotidectomy. In patients with facial nerve preservation, total parotidectomy was associated with a significant increase in transient facial weakness (72/177 (41%) vs. 82/311 (26%), RR 0.65, 95% CI 0.50-0.84, p < 0.05) and permanent facial nerve weakness (23/176 (13%) vs. 16/301 (5%), RR 0.41, 95% CI 0.22-0.75, p < 0.05) compared to superficial parotidectomy. Adjuvant radiation therapy (RT) was delivered to 285 (36%) patients. The proportion of patients receiving adjuvant RT declined significantly over the time period from 2015 to 2019 compared to 2010 to 2014 at 162/504 (32%) and 123/282 (44%), respectively (RR 0.74, 95% CI 0.61-0.89, p < 0.05). When comparing the time periods from 2015 to 2019 and 2010 to 2014, there was no significant difference in local control rates (RR 0.52, 95% CI 0.26-1.04, p = 0.06) or regional control rates (RR 0.75, 95% CI 0.26-2.13, p = 0.58).

Management of low- and intermediate-grade salivary cancer from 2010 to 2019 was variable, which is expected given the rarity and heterogeneity of the disease and the lack of treatment guidelines prior to 2021. Most patients with parotid malignancies underwent superficial or total parotidectomy. The extent of parotidectomy had an impact on facial nerve function outcomes. Delivery of adjuvant radiation trended down with time. The data presented here will support dissemination of the guidelines and provide data that could inform future trials.

2b.