Oral cavity adjuvant therapy (OCAT) -a phase III, randomized controlled trial of surgery followed by conventional RT (5 fr/wk) versus concurrent CT-RT versus accelerated RT (6fr/wk) in locally advanced, resectable, squamous cell carcinoma of oral cavity

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. 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). 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). 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. NCT00193843. •Phase III RCT comparing adjuvant radiation therapy versus CTRT versus accelerated radiation therapy in high risk oral cavity squamous cell carcinomas.•900 patients accrued (1:1:1 randomisation), positive margins in