Retrospective Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Oncol. Jan 24, 2020; 11(1): 11-19
Published online Jan 24, 2020. doi: 10.5306/wjco.v11.i1.11
Predictors of distant metastasis in acinic cell carcinoma of the parotid gland
Syed Ahmed Ali, Kevin J Kovatch, Jonah Yousif, Sonali Gupta, Andrew J Rosko, Matthew E Spector
Syed Ahmed Ali, Kevin J Kovatch, Jonah Yousif, Sonali Gupta, Andrew J Rosko, Matthew E Spector, Department of Otolaryngology - Head and Neck Surgery, Michigan Medicine, Ann Arbor, MI 48104, United States
Author contributions: Ali SA, Spector ME, and Rosko AJ designed the study; Spector ME and Rosko AJ supervised the report; Ali SA, Gupta S, and Yousif J performed the research and assisted with analysis; Ali SA, Kovatch KJ, Gupta S and Yousif J wrote the paper; Kovatch KJ, Rosko AJ and Spector ME provided clinical advice.
Institutional review board statement: This work is approved under IRB HUM00036763.
Informed consent statement: Patients were not required to give informed consent to the study because the analysis used anonymous clinical data that were obtained after each patient agreed to treatment by written consent.
Conflict-of-interest statement: The authors declare no potential conflicts of interest.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Matthew E Spector, MD, Associate Professor, Department of Otolaryngology - Head and Neck Surgery, Michigan Medicine, 1500 East Medical Center Drive, Ann Arbor, MI 48104, United States. ahmedali@med.umich.edu
Received: March 8, 2019
Peer-review started: March 11, 2019
First decision: April 15, 2019
Revised: October 14, 2019
Accepted: November 5, 2019
Article in press: November 5, 2019
Published online: January 24, 2020
ARTICLE HIGHLIGHTS
Research background

AiCC is regarded as a low-grade, indolent primary cancer of the salivary gland. There are few reports in the literature of high-grade AiCC or instances of distant metastases.

Research motivation

This study aims to further identify potential predictors of distant metastases in this predominantly low-grade carcinoma. This will allow us to identify patients at risk for distant metastases and those who should be closely followed after treatment.

Research objectives

The main objective was to identify predictors of distant metastases in patients with AiCC of the parotid gland. We were able to identify gross facial nerve invasion as a unique predictor. Realizing this objective will allow us to sequence tissue from these poorly behaving carcinoma specimens and potentially identify actionable targets.

Research methods

The research methods for this study involved utilizing a thorough search via high-yield keywords and International Classification of Diseases (ICD) codes to identify all patients with AiCC treated at the study institution. Further narrowing and identification of the final dataset was undertaken through manual means.

Research results

This study identified gross facial nerve invasion as an intra-operative predictor of distant metastases in patients with AiCC of the parotid gland. Additional factors that were associated with worse disease-free survival and overall survival included higher T-classification and high-grade disease on pathology. Further studies could sequence specimens from these patients and determine possible contributing mutations or biomarkers.

Research conclusions

This study determines that gross facial nerve invasion is an intraoperative predictor of distant metastases in patients with AiCC of the parotid gland. Patients with gross facial nerve invasion should be carefully followed and potentially screened for distant metastases as part of their post-treatment surveillance. High-grade pathology and greater T-stage are associated with worse disease-free and overall survival in this patient population. Intraoperative findings a supplement pathologic findings in determining post-operative treatment plans and need for additional screening or follow-up. The new hypothesis proposed is the potential for additional predictors of poor outcomes in a largely low-grade and indolent carcinoma. This study utilized extensive keyword and ICD code-based review of a single-insitution’s database. Gross facial nerve invasion is found to be predictive of distant metastases in AiCC of the parotid gland. This study confirmed our hypothesis that there are additional predictive clinical factors in patients with AiCC who develop distant metastases. This study can help identify patients who may benefit from closer dedicated follow-up or additional screening.

Research perspectives

Despite previous literature and similarly sized retrospective reviews, there can be additional useful information available in performing similar retrospective studies. Future research must take place on the basic science or translational level. This could entail sequencing tumor specimens of patients with distant metastatic development and identifying potential targetable biomarkers or mutations.