Published online Dec 24, 2020. doi: 10.5306/wjco.v11.i12.1029
Peer-review started: September 21, 2020
First decision: October 21, 2020
Revised: November 5, 2020
Accepted: November 28, 2020
Article in press: November 28, 2020
Published online: December 24, 2020
While mucoepidermoid carcinoma (MEC) is a rare cancer, it is the most common histologic subtype of the major salivary glands. Despite this, there is a paucity of studies with high statistical power that provide conclusions on pretreatment and treatment related factors that affect survival. This study is one of the largest population-based studies of mucoepidermoid carcinoma of the major salivary glands focused on identifying prognostic factors effecting overall survival (OS) and cause-specific survival (CSS).
While mucoepidermoid carcinoma is a rare cancer, it is the most common histologic subtype of the major salivary glands. Despite this, there is a paucity of studies with high statistical power that provide conclusions on pretreatment and treatment related factors that affect survival. By identifying prognostic factors that affect both overall OS and CSS, we hope this study can help provide information to guide and inform treatment plans for patients diagnosed with MEC of the major salivary glands.
This study is one of the largest population-based studies of MEC of the major salivary glands and sought to identify prognostic factors influencing OS and CSS of patients with MEC of the major salivary glands.
De-identified cancer registry data from the Surveillance, Epidemiology and End-Results (SEER) Database of the National Cancer Institute was used to investigate a variety of factors that could influence survival of patients diagnosed with mucoepidermoid carcinoma of the major salivary glands. The primary endpoints were OS and CSS. Cox regression analysis was used to perform univariate and multivariate analyses of clinical variables such as age at diagnosis, diagnosis year, sex, race, tumor size, stage, grade, treatment with or without surgical excision, and adjuvant radiotherapy treatment.
A total of 2210 patients diagnosed with MEC of the major salivary glands met inclusion criteria. The clinical factors that were associated with statistically significant improvements in both OS and CSS include younger age at diagnosis, smaller tumor size, lower tumor grade, localized tumor growth, female sex, and more recent year of diagnosis. Importantly, no statistically significant improvement in OS or CSS was noted with adjuvant radiation therapy following surgery.
This study identified a variety of factors that affect OS and CSS for patients with mucoepidermoid carcinoma of the major salivary glands. These factors can help inform and guide treatment planning for mucoepidermoid carcinoma of the major salivary glands. Additionally, this study provided commentary on the debate between cancer staging vs histologic grading being more predictive of clinical outcome as well as which histologic grading system should be utilized for these cancers, something that was possible due to the improved statistical power of this study.
Further research is needed to better delineate the role of adjuvant radiation for low-, intermediate-, and high-grade MEC in order to better guide treatment planning. This study did not find a statistically significant improvement in OS or CSS for patients who received adjuvant radiation therapy, though we did not analyze the effect of radiation on OS and CSS for each histologic grade or tumor stage, nor did we analyze local control of disease from adjuvant radiation therapy due to the constraints of the SEER database. Furthermore, there are currently dissenting opinions about the role of adjuvant radiation for high-grade MEC of the major salivary glands.