Post-operative accelerated hypofractionated radiotherapy for adenoid cystic carcinoma

Objective: To examine the outcomes of patients with adenoid cystic carcinoma (ACC) treated with postoperative accelerated hypofractionated radiotherapy (AHRT).Methods: Patients treated with AHRT (50-55 Gy in 20 fractions over 25 days) between 1997 and 2008 were identified and retrospectively analysed. Data collection included site of primary and surgical excision margin. Primary outcomes were overall survival (OS) and local control (LC) calculated using the Kaplan-Meier method.Results: A total of 37 patients meeting the above criteria were identified with a median age of 55 years (range 31-79). Distribution by anatomical site was as follows: parotid 9 patients; submandibular gland 8 patients; other salivary gland tissue 20 patients. Surgical excision margins were as follows: noninvolved 25 patients; microscopic involvement 7 patients; macroscopic involvement 4 patients; unknown 1 patient. Median follow-up was 59 (range 14-126) months. Five patients had local recurrence, 4 distant recurrences, and 1 both local and distant recurrence. The 5-year LC and OS rates were 81.8% (95% confidence intervals (CIs) 60.9-92.2) and 78.5% (95% CI 58.0-89.8%), respectively.Conclusion: Outcomes with post-operative AHRT appear comparable to those in the literature. However, until more is known about the radiobiology of this rare disease, a biological equivalent of 60 Gy in 2 gray fractions without correction for accelerated repopulation should be used.