Prospective Evaluation of Locoregional Control in Oral Cavity Squamous Cell Carcinoma with Infratemporal Fossa Involvement Treated with Surgery and Adjuvant Concurrent Chemoradiotherapy

Abstract

Oral cavity squamous cell carcinoma (OCSCC) is the most common head and neck cancer in India. Definitive surgery with or without post-op radiotherapy (PORT) with or without chemotherapy (CT) provides better outcomes in locally advanced OCSCC as compared to definitive chemoradiotherapy. T4b OCSCC with infra temporal fossa (ITF) involvement has varied outcome depending on the extent of ITF involvement, with low and mid ITF having relatively favorable prognosis. We aimed to prospectively evaluate outcomes in patients of OCSCC with low or mid ITF involvement treated with curative surgery followed by adjuvant concurrent chemoradiotherapy (CCRT). A total of 20 patients of T4b OCSCC (as per AJCC 8th edition) with low or mid ITF involvement were included in this single arm prospective interventional study from January 2021 to October 2022. Patients with involvement of skull base, carotid artery, prevertebral fascia and/or pterygomaxillary fissure were excluded. All patients were treated with definitive surgery with ITF clearance followed by adjuvant CCRT as indicated. Loco-regional control (LRC), Disease free survival (DFS), Overall survival (OS) were assessed using Kaplan-Meier survival analysis. Acute toxicities were assessed according to the CTCAE v5.0. Patient characteristics are summarized in table 1. Median follow-up was 11.5 months (4-21months). All patients received adjuvant CCRT with weekly cisplatin 40mg/m2 to a median number of 6 cycles (5-7 cycles). Median RT dose was 64Gy (60-64Gy). All patients tolerated treatment well. Grade 3 oral mucositis, odynophagia were seen in 8 (40%) patients each and skin toxicity, oral pain in 6 (30%) and 5 (25%) patients respectively. No grade 4 toxicities were observed LRC at three month was 73.68% with 4 local and 1 locoregional failure only. LRC at one year was 36.8% with 8 local, 1 locoregional, 2 locodistant and 1 distant failure only. Median DFS was 10.4 months. Median OS was not reached; four patients died. LRC at three months was better for patients with low ITF disease as compared to mid ITF disease (85.7% vs. 40% (p = 0.04) and at one year was 42.8% vs. 40% (p = 0.50). Selected patient of locally advanced OCSCC with low ITF involvement may benefit from trimodality therapy of surgery with ITF clearance followed by adjuvant CCRT. Acute toxicity profile was acceptable in our study.