Malignant salivary gland tumors in Quito, Ecuador.

OBJECTIVES: Malignant salivary gland tumors (MSGT) are uncommon. Age-standardized incidence rates are 0.5 and 0.3 per 100,000 in Quito, Ecuador; and 1.0 and 0.7 per 100,000 in the USA (SEER Program), for males and females, respectively. The goal of this study was to review a 16-year experience of a major general hospital in the treatment of these lesions.

PATIENTS AND METHODS: From 1982 to 1998, 308 salivary gland tumors were surgically treated at the Hospital 'Carlos Andrade Marin' of the Ecuadorian Institute of Social Security in Quito, Ecuador, an Andean city of approximately 2 million inhabitants. Malignant lesions were found in 58 cases (19%): 37 out of 194 parotid gland tumors (19%), 7 out of 86 submandibular tumors (8%) and 14 out of 28 minor salivary gland tumors (50%). Adenoid cystic carcinoma and mucoepidermoid carcinoma were the most common histologic types. Twenty-two cases were classified as stage I, 13 as stage II, 1 as stage III and 20 as stage IV (UICC TNM staging classification). Thirty-one (53%) patients were treated by surgery alone; postoperative radiation therapy was additionally given to 22 (38%), and surgery, radiotherapy and chemotherapy were applied in 5 cases (9%).

RESULTS: Local (LR) and/or regional recurrences were detected in 13 patients (22%). Twelve patients (21%) developed distant metastasis (DM; 2 in more than one site): 7 in the lungs, 2 in the brain, 2 in the bone and 1 each in the liver, subcutaneous tissue and pleura. Thirty-five patients are alive, 33 disease free. Twenty-three patients are deceased: 6 with LR, 7 with DM, 3 with both LR and DM, 1 with locoregional recurrence and DM, 2 with a second neoplasm, 3 with intercurrent disease and 1 from unknown causes. Five- and 10-year overall survival rates were 75 and 68%, respectively. There were no significant differences in mortality according to the site of the primary tumor or histologic type, but stage and involved surgical margins were important prognostic factors (p = 0.006 and 0.003).

CONCLUSIONS: The surgical or multimodality treatment of MSGT has provided a good locoregional control (78%) and 68% 10-year survival in a series of patients treated at the oncology department of a general hospital in Quito, Ecuador. Stage and involved surgical margins were significant prognostic factors.