Background: Limited data exists regarding the impact of intensification of adjuvant therapy in resected Oral Cavity Squamous Cell Carcinomas (OCSCC) with adverse prognostic features on histopathology.
Patients and methods: This was a three-arm phase III, randomised trial including patients with resected advanced OCSCC. Randomisation was done in a 1:1:1 ratio: Arm-A- standard adjuvant radiation therapy (RT) 60Gy/30 fractions over 6 weeks versus Arm-B-concurrent chemoradiation versus Arm-C-accelerated radiation therapy (6 d a week). The trial was powered to detect an absolute difference of 10% in 5-year Locoregional Control (LRC).
Results: The trial was conducted between June 2005 and March 2013. Majority of the patients were males, had T3-T4 disease, had N2-N3 nodal status and had Extra-Capsular Extension (ECE) in nodes. The median follow-up was 95.9 months. There was no difference between the three arms (A versus B versus C) for 10-year locoregional control (LRC): 60.2% versus 61.4% versus 65.7%, p = 0.57; disease free survival (DFS): 37.4% versus 43.9% versus 39.6%, p = 0.40; or Overall Survival (OS): 39.7% versus 46.6% versus 40.4%, p = 0.40. There was no benefit of intensification with either modality in patients with any single adverse pathological factor. A benefit of intensification could be seen in patients with a combination of high-risk features: T3-T4 primary tumours with N2-N3 nodes along with ECE for DFS (Arm B versus Arm A HR) = 0.53, Arm C versus Arm A HR = 0.63) and OS (Arm B versus Arm A HR = 0.58, Arm C versus Arm A HR = 0.60).
Conclusions: All optimally resected OCSCC with adverse features did not benefit from intensification of adjuvant therapy. Only a cohort of patients with a combination of high-risk features are likely candidates for intensification.
Clinical trial registration: NCT00193843.
Keywords: Adjuvant therapy; Chemoradiation; Oral cavity; Squamous carcinoma; Treatment intensification.
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