Abstract A21: Increasing use of adjuvant radiation for parathyroid carcinoma is associated with improved survival outcomes: A population-based study

Abstract

Abstract Objectives: Parathyroid carcinoma is rare and treatment for these cancers varies between institutions. The primary purposes of this study were to use the Surveillance, Epidemiology, and End Results (SEER) database to evaluate current practice patterns in the use of adjuvant radiation for parathyroid cancers and to investigate the efficacy in a population-based setting. Methods: There were 508 patients treated surgically for parathyroid cancer from 1973 to 2013 identified in the SEER database. Patients with metastatic disease and other prior malignancies were excluded. Three hundred and twenty-one patients (63%) had local disease, while 187 had regional lymph node involvement (37%). Of these patients, 78 (15%) were treated with adjuvant radiation. 5-year disease-specific survival (DSS) and overall survival (OS) were the primary outcomes. Results: Treatment with adjuvant radiation therapy was significantly associated with improved 5-year DSS (94% versus 89%; p=0.045) and OS (81% versus 74%; p=0.036). Improved DSS and OS were significant after controlling for other known covariates on multivariate analysis (HR 0.59, 95% CI 0.44-0.87, p<0.001; HR 0.65, 95% CI 0.47-0.92, p<0.001). The percent utilization of adjuvant radiation for patients with parathyroid carcinoma has significantly increased through the study time period from 7% (1973 to 1986) to 11% (1987 to 2000) to 18% (2001 to 2013) (p=0.011). Conclusion: Adjuvant radiation appears to provide a survival benefit for patients with parathyroid carcinoma. Utilization of adjuvant radiation is increasing over time for these patients. Citation Format: Richard B. Cannon, Patrick S. Carpenter, Luke O. Buchmann, Jason P. Hunt, Shane Lloyd, Ying Hitchcock, Marcus M. Monroe. Increasing use of adjuvant radiation for parathyroid carcinoma is associated with improved survival outcomes: A population-based study [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr A21.