Management and Outcome of Patients With Malignant Salivary Gland Tumors

Abstract

Refined imaging technology, the use of external beam radiation, neutron beam therapy, and chemotherapy, has altered management strategies for patients with salivary gland malignancies during the past 2 decades. Although treatment remains primarily surgical, optimal therapeutic regimens have yet to be fully realized. The purpose of this investigation is to report our experience with the management of patients with a variety of malignant salivary gland neoplasms that were treated with various combinations of surgery, radiation, and chemotherapy and to review treatment outcome in an effort to identify predictors of survival and locoregional control. The records of all patients with malignant salivary gland tumors presenting for treatment at our institution between 1992 and 2002 were retrospectively reviewed. Variables were collected and outcome measures were defined in terms of overall survival, disease-free survival, and locoregional control. Descriptive statistics were compiled and statistically evaluated. Survival was described using the Kaplan-Meier method. Prognostic factors were assessed using the Cox proportional hazards model. Clinical and reconstructive factors were reviewed. Eighty-five patients (35 males and 50 females) ranging in age from 16 to 89 years (mean, 58.6 years) met the criteria for inclusion in the study. The majority of tumors were located in the parotid gland (n = 42), with a significant minority located in the minor salivary glands (n = 29), followed by the submandibular gland (n = 8) and the sublingual gland (n = 6). Mucoepidermoid carcinoma was the most common neoplasm (n = 40). More than half of the patients presented in early-stage disease (stage I = 36, stage II = 17, stage III = 8, stage IV = 25). All patients were treated with surgery as the primary modality. Neck dissection was performed in 29% of patients, and more than half (56%) were treated with adjuvant external beam radiation therapy to a dose of 50 to 70 Gy. Patients were, in general, immediately reconstructed at the time of ablation using composite free tissue transfer when appropriate, local/regional rotational flaps, or maxillary obturators. The disease-free survival rate and locoregional control rate at 5 years were 77% and 86%, respectively. Stage (P = .0017), grade (P = .00044), cervical lymph node metastasis (P = .03), and age (P = .01) proved to make a statistically significant contribution when describing outcome. Neither site (P = .5), the presence of positive margins (P = .3), nor perineural invasion (P = .7) had a significant impact on survival. The treatment of salivary gland malignancies remains primarily surgical, although adjunctive radiotherapy may play an important role in those patients with advanced-stage disease. This study confirms the contributions of stage, grade, age, and cervical metastasis for describing survival. The benefits of combined modality therapy awaits prospective clinical trials.