High-grade malignancies of the parotid gland: effective use of planned combined surgery and irradiation.

The trend toward treatment of parotid gland malignancies with planned combined surgery and postoperative radiation therapy is currently being followed by many centers, although prospective studies confirming the efficacy of this treatment regimen have only recently begun. We have reviewed only our "high-grade" histologic types: adenocarcinomas, malignant mixed tumors, high-grade mucoepidermoid carcinomas, squamous cell carcinomas, and undifferentiated carcinomas. Acinic cell carcinomas, adenoid cystic carcinomas, and low-grade mucoepidermoid carcinomas were excluded from study because of their different biologic behavior. Since 1974, we have employed the approach of surgical extirpation with preservation of the facial nerve when possible for all parotid tumors, combined with planned postoperative radiation therapy (50-70 Gy). We reviewed the 37 cases of "high-grade" parotid gland malignancies and compared the patients treated with the combined modality approach with our historical patients treated initially with surgery alone. Despite an apparent higher stage at presentation, our combined treatment group ultimately had significantly better local control (70% vs. 20%), and an equivalent survival rate at five years. Tumor was present at the margin of resection in 14 (74%) cases treated with combined surgery and irradiation. The facial nerve was preserved in six of these patients with positive margins, and only one of these patients developed a local or regional treatment failure. In conclusion, our data confirms the efficacy of surgical exploration to determine the extent of disease and surgical resection, preserving facial nerve function if possible, followed by postoperative radiation therapy at adequate doses. Control of local-regional disease was much improved by combined modality therapy as opposed to surgical resection alone, despite the prevalence of residual microscopic disease in the resection margins. Facial nerve function is optimally preserved by this approach of conservative surgery combined with postoperative radiation therapy.