Predictors of early progression after curative resection followed by platinum-based adjuvant chemoradiotherapy in oral cavity squamous cell carcinoma

Objectives: Early progression, defined as a disease-free interval (DFI) of less than 6 months after completion of adjuvant platinum-based chemoradiotherapy (CRT), leads to poor outcomes in locally advanced oral cavity squamous cell carcinoma (OCSCC). However, appropriate biomarkers for predicting early progression remain unknown. Methods: In this study, 346 patients with OCSCC, who underwent curative surgical resection and platinum-based adjuvant CRT at the Taipei Veterans General Hospital (202 patients, training cohort) and Chung Shan Medical University Hospital (144 patients, validation cohort) were enrolled. The clinical–pathological variables were compared using the χ² test. Cox proportional-hazards analyses were performed for DFIs. Survival was estimated using the Kaplan–Meier method and log-rank tests, and a scoring system for predicting early progression was established. Results: One-fifth (20.5%, 71/346) of all patients experienced progression within 6 months. Each of the independent factors for the DFI in the training cohort, including pT3-4, extracapsular spread, and perineural invasion, were assigned a score of one point to establish a scoring system. The 6-month DFIs of the low-risk (score 0–1), intermediate-risk (score 2), and high-risk (score 3) groups were 97.8%, 78.7%, and 35.7% and 88.2%, 77.6%, and 42.1% in the training and validation cohorts, respectively. If the cutoff level was ≥2 or <2, the sensitivity/specificity/area under the curve for the training and validation cohorts were 94.4%/56.1%/0.837, and 73.3%/56.6%/0.703, respectively. Conclusions: The established scoring system effectively predicted early progression after adjuvant CRT for locally advanced OCSCC.