3710 - Cesium-131 Brachytherapy in Patients that are Not Candidates for Post-Operative External Beam Radiation Therapy: Interim Results of a Single Arm Prospective Study

B. Parashar¹, L. Pereira², D. Kamdar², G. Har-El³, L. Krevitt⁴, B. A. Miles⁵, L. Wang⁶, F. Tran⁷, D. Knobel⁸, D. Hirsch⁷, and D. Frank⁸; ¹Northwell, Lake Success, NY, ²Northwell Health, New Hyde Park, NY, ³Northwell Health Lenox Hill Hospital, New York, NY, ⁴Lenox Hill Hospital, Northwell Health, New York, NY, ⁵Department of Otolaryngology, Northwell Health, New York City, NY, ⁶Department of Radiation Medicine, Northwell, Lake Success, NY, ⁷Northwell Health, New York, NY, ⁸Northwell Health, Lake Success, NY

Purpose/Objective(s):

Patients with advanced head and neck cancers (HNC) that present with resectable disease but are not candidates for post-operative external beam radiation pose a unique challenge. Reasons for ineligibility may include poor-performance status, prior-radiation therapy, or patient choice. We report an interim report of toxicity and outcomes of our institutional prospective study using Cesium-131 (Cs-131) brachytherapy at the time of surgery. Materials/

Methods:

This is an IRB approved prospective single arm study. Eligibility includes operable advanced HNC needing post-operative external beam radiation (EBRT). Reasons for deciding against EBRT post-operatively included prior full course RT, patient choice, and performance status. Surgery includes gross total resection followed by Cs-131 implantation of the tumor bed, seeds 1 cm apart. Immediate reconstruction was performed if necessary. All patients were evaluated every 2-4 months for the first 12 months, followed by evaluation every 3-6 months. Recurrence was evaluated by clinical examination, contrast CT and/or FDG-PET. Toxicity was assessed using CTCAE v.5 criteria. Survival estimates were performed using the Kaplan-Meier method. Local control was defined as no recurrence within 0.5cm of the implant site.
Results:

Eleven patients have been accrued till date in this study. Median age is 73 (Range 60-95). There were 3 females (27%) and 8 males (73%). Primary tumor sites are 7 (63%) oral cavity, 2 (18%) oropharynx, 1 larynx and 1 salivary gland. Nine patients had Cs-131 neck implant while 2 patients primary site implanted. Median prescription dose was 80Gy (Range:70-80Gy). Six patients had prior RT to the implanted site. Seven (63%) patients were treated for recurrent disease. With a median follow-up of 8 months (Range 1-19),11/11 (100%) patients had local control at the implanted site, 4/7 (37%) patients developed regional recurrence, 2 patients developed distant recurrence. At the last follow-up 8/11 (72%) are alive. There were four patients with grade 2 toxicity including abscess formation, flap dehiscence, skin breakdown, fistula (not ascribed to seeds) all of which were managed conservatively, and fistula was repaired. One patient had a short follow up of 3 months and was reported to have expired although the cause could not be ascertained.
Conclusion:

This is an interim report of a prospective study using Cs-131 in HNC that were not candidates for curative post-operative EBRT. The high local control rates and limited toxicity are encouraging. We continue to accrue patients in this study and will report longer term outcomes of this prospective study soon.