Fractionated Radiotherapy for Pleomorphic Adenoma

Abstract

Purpose/Objective(s)Pleomorphic adenoma is the most common benign salivary gland tumor. It is primarily treated with definitive surgery. Rarely, radiation therapy can be utilized for recurrent lesions and in other scenarios such as positive margins. There are relatively few studies reporting efficacy and outcomes of pleomorphic adenoma treated with radiation therapy. The purpose of this project is to report tumor control, complications, and survival outcomes of patients treated with fractionated radiotherapy at our institution with pleomorphic adenoma.Materials/MethodsThis was a retrospective analysis of survival outcomes and treatment-related toxicity in patients with pleomorphic adenoma treated with fractionated radiotherapy at our institution between 1970 and 2016. We excluded patients who did not have a histologic diagnosis and those with prior unrelated head or neck radiation. We identified 35 patients who met these criteria. The Kaplan-Meier product limit method was utilized to assess time-dependent endpoints.ResultsMedian clinical follow-up was 9.1 years and median imaging follow-up was 6.9 years. The 15-year cause-specific survival rate was 86% and the 15-year overall survival rate was 68%. The rate of 15-year local control was 64%; however, 42% of patients with local failures were ultimately successfully controlled with salvage therapies. The rate of patients who experienced grade 3 or higher CTCAE toxicity was 17%.ConclusionTo the best of our knowledge, this study comprises the largest cohort of pleomorphic adenoma patients treated with fractionated radiotherapy in the last 25 years. Our data suggests that radiation therapy is efficacious and minimally toxic in this rare clinical scenario. Furthermore, in patients who do recur following radiation therapy, there is a relatively high rate of successful salvage. Pleomorphic adenoma is the most common benign salivary gland tumor. It is primarily treated with definitive surgery. Rarely, radiation therapy can be utilized for recurrent lesions and in other scenarios such as positive margins. There are relatively few studies reporting efficacy and outcomes of pleomorphic adenoma treated with radiation therapy. The purpose of this project is to report tumor control, complications, and survival outcomes of patients treated with fractionated radiotherapy at our institution with pleomorphic adenoma. This was a retrospective analysis of survival outcomes and treatment-related toxicity in patients with pleomorphic adenoma treated with fractionated radiotherapy at our institution between 1970 and 2016. We excluded patients who did not have a histologic diagnosis and those with prior unrelated head or neck radiation. We identified 35 patients who met these criteria. The Kaplan-Meier product limit method was utilized to assess time-dependent endpoints. Median clinical follow-up was 9.1 years and median imaging follow-up was 6.9 years. The 15-year cause-specific survival rate was 86% and the 15-year overall survival rate was 68%. The rate of 15-year local control was 64%; however, 42% of patients with local failures were ultimately successfully controlled with salvage therapies. The rate of patients who experienced grade 3 or higher CTCAE toxicity was 17%. To the best of our knowledge, this study comprises the largest cohort of pleomorphic adenoma patients treated with fractionated radiotherapy in the last 25 years. Our data suggests that radiation therapy is efficacious and minimally toxic in this rare clinical scenario. Furthermore, in patients who do recur following radiation therapy, there is a relatively high rate of successful salvage.