Postoperative Adjuvant Radiotherapy for Adenoid Cystic Carcinoma of the Head and Neck: Treatment Results and Prognostic Factors

Background: To analyze the treatment results and prognostic factors of patients with adenoid cystic carcinoma (ACC) arising from the major and minor salivary glands of the head and neck, and who received postoperative radiotherapy after radical tumor resection. Methods: Between October 1987 and December 1999, 25 patients with ACC of the head and neck were treated with radical surgical resection and postoperative adjuvant irradiation without chemotherapy. Using appropriate radiation techniques to the tumor bed, total doses ranged from 44 to 68.4 Gy. All patients had a minimum of 2 years of follow-up. Results: The 5-year overall survival rate, local control rate, and distant metastasis-free rate were 75%, 83%, and 66%, respectively. To the present, 2 patients had experienced recurrence at the primary sites, and 1 had regional lymph node metastasis. Distant metastases developed in 7 patients (28%), of whom 6 (86%) were disease-free at the primary site. The lung was the most common distant metastatic site. In multivariate analysis, the only statistically significant prognostic factor for a distant metastasis-free rate was the stage at presentation (p = 0.009). Conclusion: Patients with an advanced stage of disease had higher distant metastasis rates even when receiving postoperative radiotherapy. Distant metastasis is still the main problem in the management of ACC of the head and neck. However, more-effective treatment for this problem is still lacking.