Intraoperative radiation therapy for locally advanced and recurrent head and neck cancer.

Abstract

6058 Background: Intraoperative Radiation Therapy (IORT) allows precise delivery of radiation therapy (RT) to a limited target area at high risk of cancer recurrence while minimizing RT to nearby organs at risk. IORT may be particularly beneficial for patients with locally recurrent head and neck cancer (HNC) in a previously irradiated field and for locally advanced HNC cases, in which obtaining negative surgical margins may be difficult. This study aims to present a single institution experience with IORT for HNC patients. Methods: This study included HNC patients treated consecutively with IORT at our institution between 2014 and 2018. Charts were reviewed for patients’ and tumors’ characteristics, IORT technical details, IORT-induced adverse events, and treatment outcomes. Results: The study included 23 eligible patients. Median patient age was 66 (range 33-91). Tumor sites included parotid gland (43%), lymph nodes (43%), oral tongue (9%), and ear (4%). 52% of patients received IORT upfront with or without postoperative adjuvant external beam radiation therapy (EBRT), while 48% received salvage IORT after local tumor recurrence. The median prescribed IORT dose was 7.5 Gy (range 5-14 Gy) in a single fraction prescribed to 5 mm depth with Flat applicators (median diameter of 5 cm). 92% of patients did not experience wound healing complications. One patient (4%) developed postoperative acute thromboembolic stroke, a second patient (4%) experienced protracted wound healing. At a median follow-up of 36 months (range 2-81), 42% of patients presented with no evidence of disease (NED), overall survival was 54%, 13% of patients were alive with disease, and 46% died with disease. Local-regional recurrence rate was 39% (median time to local recurrence was 18 months, range 2-60), rate of distant metastasis was 43% (median time to distant metastasis was 23 months, range 5-60), and 30% of patients had both local-regional recurrence and distant metastases. The percent of local-regional recurrence and distant metastases among patients receiving salvage IORT was 64% and 73% respectively, compared to 23%, and 15% respectively in those receiving upfront IORT with or without adjuvant EBRT. Conclusions: In this single institution chart review study, IORT to locally advanced and recurrent HN cancer patients was a safe treatment modality, with tumor control comparable to historical EBRT data. Larger prospective studies are needed to further assess the utility of IORT in the management of locally advanced and recurrent HN cancer.