Five- and 10-Year Cause-Specific Survival Rates in Carcinoma of the Minor Salivary Gland

IMPORTANCE Previous studies of prognostic factors of carcinoma of the minor salivary gland (MSG) have been limited to single-institution studies and small case series. Thus, limited data are available to guide the head and neck oncologist in counseling patients on the prognosis and management of these malignant neoplasms. OBJECTIVE To examine 5-and 10-year cause-specific survival (CSS) rates of MSG carcinomas across all histologic subtypes and head and neck tumor subsites. DESIGN, SETTING, AND PATIENTS Retrospective, population-based study using National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) data from January 1, 1988, through December 31, 2009. The study included 5334 patients diagnosed as having MSG carcinoma and registered in the SEER database. Patients without follow-up, diagnostic confirmation, and/or race designation were excluded from the analysis (131 [2.4%]). Final follow-up was completed on December 31, 2009, and data were analyzed from August 5, 2013, to July 1, 2014. MAIN OUTCOMES AND MEASURES Five-and 10-year CSS rates for US patients with MSG carcinoma. Cox proportional hazard models were used to estimate adjusted hazard ratios (HRs) and 95% Cls. RESULTS Among the 5334 patients with MSG carcinoma included, the most common histologic subtypes included mucoepidermoid carcinoma (1568 [29.4%]), adenoid cystic carcinoma (1228 [23.0%]), and adenocarcinoma (1313 [24.6%]). The most frequent sites of primary tumor were the oral cavity (3132 [58.7%]) and pharynx (1130 [21.2%]). Five-year CSS rate was significantly worse for MSG malignant neoplasms located in the larynx (HR, 2.42; 95% Cl, 1.67-3.50) and nasal cavity and/or paranasal sinus (HR, 1.73; 95% Cl, 1.29-2.32). Being older than 75 years was associated with a significantly worse 5-year CSS rate (HR, 2.88; 95% Cl, 2.05-4.06). Compared with no surgery, local tumor destruction (HR, 0.44; 95% Cl, 0.30-0.64), partial surgery (HR, 0.33; 95% Cl, 0.23-0.47), and total surgery (HR, 0.55; 95% Cl, 0.41-0.74) were each found to be a significant positive prognostic factor. No differences were observed in the 5-year hazard of death for race/ethnicity, sex, diagnosis year, or socioeconomic status, and 10-year adjusted HRs were similar to the 5-year patterns. CONCLUSIONS AND RELEVANCE This study, to date, represents the largest US survival analysis of carcinoma of the MSG. Prognosis is associated with histologic subtype, tumor subsite, age at diagnosis, grade, and surgical therapy.