Overall survival (OS) and risk of distant failure among malignant salivary gland tumors (MSGTs) in a large single-institution registry cohort.

Abstract

e16045 Background: MSGTs are rare, biologically diverse cancers. Registry data and large series suggest 5-year OS exceeding 50%, superior to historical data and attributed to postoperative radiation (pXRT). Hypothesizing OS has remained poor despite modern therapy, we reviewed our cancer registry (OHSUCR), which began collecting data on MSGTs in 1995. Methods: We interrogated the OHSUCR for pts with MSGTs (WHO classification) and obtained data on age, sex, race, AJCC stage, histology, primary site, surgery, pXRT. OS was estimated using the Kaplan Meier (KM) method. The log rank test was used to compare OS among pts treated with and without pXRT, and those diagnosed between 1995-2000, 2001-2005, and 2005-present. Results: 110 pts with MSGTs were entered into the OHSUCR from 5/1996 to 5/2011. The median age was 60 (range 10-90), 65 (59%) were male, and 106 (96%) were white. The primary site was: 101 (92%) parotid, 3 (3%) unspecified major salivary gland, 4 (3%) submandibular gland, and 2 (2%) minor salivary gland. MSGT histologies were: 41 (37%) mucoepidermoid carcinoma, 24 (22%) adenoid cystic carcinoma, 21 (19%) adenocarcinoma, 12 (11%) acinar cell carcinoma, 5 (4%) carcinoma ex pleomorphic adenoma, 3 (3%) epithelial-myoepithelial carcinoma, 1 (1%) undifferentiated carcinoma, 1 (1%) small cell carcinoma, 1(1%) salivary duct carcinoma, 1 (1%) carcinosarcoma. AJCC Stage was: I in 29, (26%) II in 20 (18%), III in 16 (15%), IV in 45 (41%). 102 (96%) underwent surgical resection, 73 (66%) pXRT. 89 (81%) pts were rendered disease free, although 23 (21%) eventually recurred, 20 in distant sites. At the time of analysis 57 (52%) pts were alive and disease free. With a median follow up of 30 months (range 1 to 165), the 5 year KM OS for the entire cohort is 46%. Median survival was not influenced by pXRT (p=0.93) or period of diagnosis (1995-2000, 2001-2005, or 2005-present; p=0.83). Conclusions: In this large single institution series, pts with MSGT remain at high risk for mortality despite routine administration of pXRT. Distant metastasis is the most common pattern of failure indicating a clear unmet need for improved systemic therapy for MSGTs.