Overall and cause-specific survival for mucoepidermoid carcinoma of the major salivary glands: Analysis of 2210 patients.

BACKGROUND: Mucoepidermoid carcinoma (MEC) is a rare malignancy of the head and neck; however, it accounts for a majority of the tumors of the salivary glands. This study used a national population-based registry to describe the pre-treatment and treatment-related prognostic factors that influence survival in patients with MEC of the major salivary glands. To our knowledge, this is the largest population-based study examining predictors of both overall and cause-specific survival of MEC of the major salivary glands.

AIM: To identify prognostic factors influencing overall survival (OS) and cause-specific survival (CSS) of patients with MEC of the major salivary glands.

METHODS: We used the Surveillance, Epidemiology and End-Results Database of the National Cancer Institute to investigate a variety of factors that could influence survival of patients diagnosed with mucoepidermoid carcinoma of the major salivary glands. A total of 2210 patients diagnosed with MEC of the major salivary glands during the years of 1975-2016 were studied. 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.

RESULTS: A total of 2210 patients diagnosed with MEC of the major salivary glands met inclusion criteria. In this study, 95% of patients underwent surgical excision and 41% received adjuvant radiation therapy. Median OS time for Grade I, II, and III/IV was 401 mo (± 48.25, 95%CI), 340 mo (± 33.68, 95%CI) and 55 mo (± 11.05, 95%CI), respectively. Univariate analysis revealed that lack of surgical excision was associated with decreased OS [hazard ratio (HR) 4.26, P < 0.0001] and that patients with localized disease had improved OS compared to both regional and distant disease (HR 3.07 and 6.96, respectively, P < 0.0001). Additionally, univariate analysis demonstrated that male sex, age over 50 at diagnosis, Grade III tumors, and increasing tumor size were associated with worsened OS ( P < 0.0006). Univariate analysis of CSS similarly revealed that lack of surgical excision and Grade III carcinoma conferred decreased CSS (HR 4.37 and 5.44, respectively, P < 0.0001). Multivariate analysis confirmed that increasing age, in 10-year age bands, advanced tumor stage, increasing tumor size, Grade III carcinoma, male sex, and lack of surgical excision were associated with a statistically significant decrease in OS and CSS ( P < 0.04). Of note, multivariate analysis revealed that the use of adjuvant radiation therapy was not associated with improved OS or CSS.

CONCLUSION: Multivariate analysis demonstrated increasing age, advanced tumor stage, increasing tumor size, Grade III carcinoma, male sex, and lack of surgical excision were associated with decreased OS and CSS ( P < 0.04).