Prognostic triad: a novel method for decision-making for adjuvant treatment in stage I-II oral squamous cell carcinoma.

This study proposes a scoring system for adjuvant irradiation for stage I/II oral squamous cell carcinoma (OSCC). Derivation cohort (119 patients, operated between 2011 and 2014) and a validation cohort (204 patients, operated between 2016 and 2019) were included. In derivation cohort, on univariate analysis, tumor size >2 cm [3-year Disease Free Survival (DFS) 72.5% vs 95.6%, P = 0.039], lymphovascular invasion (58.3% vs 83.6%, P = 0.024), perineural invasion (75% vs 85.6%, P = 0.013), and depth of invasion >/=0.5 cm (73.8% vs 97.5%, P = 0.017) predicted 3-year DFS. Tongue lesions and poor differentiation were added as poor prognosticators based on previously published reports. Patients were grouped as low risk (<3 risk factors) and high risk (>/=3 risk factors), with only high-risk group receiving adjuvant irradiation in validation cohort. Overall, 47/119 (39.5%) patients in the derivation cohort and 50/204 (24.5%) patients in validation cohort received adjuvant irradiation. In derivation cohort, 3-year DFS was 93% and 72.5% in the low and high-risk group, respectively. 3-year DFS was 90.7% and 85.8% in the low and high-risk group, respectively for validation cohort. The proposed scoring system reduced the use of adjuvant irradiation by 38%, with similar DFS.