Survival Outcomes of Adjuvant Radiation in Parotid Adenoid Cystic Carcinoma: A National Cancer Database Study

Sunday, October 12, 2025

1:18 PM - 1:24 PM EDT

Location: 127

Disclosure(s):

Marium Ansari, BS:

faculty for this accredited education activity has no relationship(s) with ineligible companies to disclose.

Janice L. Farlow, MD, PhD:

faculty for this accredited education activity has no relationship(s) with ineligible companies to disclose.

Introduction: Parotid adenoid cystic carcinoma (ACC) is a rare tumor with poor long-term survival. Microsatellites and perineural invasion are common; thus adjuvant radiation is routinely administered. Parotidectomy is the mainstay of treatment. Margin status is of particular importance due to the tendency for microscopically positive margins and perineural invasion along the facial nerve. Factors influencing survival are not well delineated. This study aims to determine the association of positive margins and adjuvant radiation with overall survival in parotid ACC.

Methods: A retrospective analysis of patients diagnosed with parotid ACC from 2004-2021 who underwent upfront definitive surgical excision was performed using the National Cancer Database (NCDB). Outcome measurements included 10-year overall survival (OS). Kaplan-Meier (KM) and Cox proportional hazard modeling was used.

Results: Of 1360 subjects, mean age was 56.1 years (range 18-90), 61.6% were female, 80.4% were white, and mean follow-up time was 89.4 months. Margins were negative in 707 cases (52.0%), with microscopic positive margins in 400 (29.4%) patients. Total parotidectomy was most commonly performed (n=713 [52.4%]), with facial nerve sacrifice in 36.0% of cases (n=489). 10-year OS was 0.632 (95%CI = [0.601, 0.663]). Patients with positive margins had significantly worse OS (HR [95%CI] = 1.43 [1.15, 1.77]), as did males (HR [95%CI] = 1.26 [1.03, 1.55]), older patients (HR [95%CI] = 1.04 [1.03, 1.05]), and those with advancing stage. Neither adjuvant radiation nor chemotherapy had a significant effect on OS.
Subgroup KM analysis of early-stage tumors (pT1N0-pT2N0) did not show any survival benefit of adjuvant radiation (total n=590; RT (n=429) vs none (n=161); p=0.15), nor among patients with microscopically positive margins (total n=372; RT (n = 343) vs none (n=57); p=0.8).

Conclusions: Surgically resected parotid ACC frequently exhibits positive margins, with adjuvant radiation given in the majority of cases. With the inherent limitations of retrospective analyses of the NCDB, radiation had no significant difference in 10-year OS.

Presenting Author(s)

EK

Evan S. Kominsky, BA

Department of Otolaryngology-Head and Neck Surgery, Icahn School of Medicine at Mount Sinai, United States

Disclosure information not submitted.
Marium Ansari, BS

Medical Student
Indiana University School of Medicine
Granger, IN, United States

Disclosure(s):
faculty for this accredited education activity has no relationship(s) with ineligible companies to disclose.

Co-Author(s)

Marium Ansari, BS

Medical Student
Indiana University School of Medicine
Granger, IN, United States

Disclosure(s):
faculty for this accredited education activity has no relationship(s) with ineligible companies to disclose.
MM

Michael G. Moore, MD

Professor
Indiana University Health
Indianapolis, Indiana, United States

Disclosure information not submitted.
MS

Michael W. Sim, MD

Associate Professor
Indiana University School of Medicine
Zionsville, IN, United States

Disclosure information not submitted.
AM

Avinash V. Mantravadi, MD

Associate Professor of Clinical Otolaryngology - Head and Neck Surgery
Indiana University
Indianapolis, IN, United States

Disclosure information not submitted.
JY

Jessica A. Yesensky, MD

Assistant Professor of Otolaryngology - Head and Neck Surgery
Indiana University School of Medicine
Indianapolis, Indiana, United States

Disclosure information not submitted.

Senior Author(s)

Janice L. Farlow, MD, PhD

Assistant Professor
Indiana University
Indianapolis, IN, United States

Disclosure(s):
faculty for this accredited education activity has no relationship(s) with ineligible companies to disclose.