OP92 – External Beam Radiotherapy (EBRT) in Radioactive Iodine (RAI) Refractory Thyroid Carcinoma: Long Term Outcomes and Toxicities

      Dhanireddy, Bhaswanth1; Burnett, Nicholas1; Ain, Kenneth2; Valentino, Joseph3; Gal, Thomas3; Kudrimoti, Mahesh1 1 Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA 2 Department of Endocrinology, University of Kentucky, Lexington, KY, USA 3 Department of Otolaryngology-Head and Neck surgery, University of Kentucky, Lexington, KY, USA   Background/Purpose: The randomized evidence for external radiation in RAI-refractory differentiated thyroid carcinoma (DTC) is limited. The goal of our study is to report outcomes, and long-term toxicities in EBRT-treated patients. Methods: IRB approved retrospective review of EBRT-treated DTC pts between 1990 – 2015 was performed. Results: Sixty-six patients were identified. The median age was 53.5 years. 52 patients (78.8%) had papillary, 5 patients (7.6%) had follicular, 3 patients (4.5%) had medullary  and 6 patients (9.1%) had mixed histologies. All pts underwent definitive surgical treatment. 58 pts (87.9%) received adjuvant RAI ablation. Median time to recurrence from diagnosis was 26.5 months (range 2–274 months). 58 (87.9%) had nodal failure and the rest had loco-regional failure with limited lung metastases. Median dose of EBRT was 60Gy (range 48.6-73.75Gy). 45 (68.2%) pts were treated with intensity-modulated radiation therapy (IMRT), 21 (48.7%) pts were treated with a 3D technique. Median follow-up was 53.8 months. For pts with only nodal recurrence, the control rate was 87.9% (51/66) vs 60% ( 6/10) in pts with metastatic disease. Reoperation following EBRT was required in only 4 (6.1%) pts. Grade-1 or higher chronic dysphagia was seen in 19pts (28.7%). 5 (7.5%) had esophageal stricture requiring dilatation, of which 3 /5 required PEG placement. 20 (30.5%) developed grade-1 or higher xerostomia, 3 (4.5%) developed chronic dental issues. Conclusion: In our series of 66 pts, the majority remained disease-free nearly 5-years post-EBRT with acceptable rates of any dysphagia/xerostomia. The need for multiple surgeries is reduced.


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