AJCC staging evolution and its clinical impact on resectable oral cancers: A decade-based cohort analysis.

PURPOSE: To assess clinical impact of American Joint Committee on Cancer (AJCC) 7th, 8th, and 9th edition transitions and staging patterns on resectable oral squamous cell carcinoma (SCC).

METHODOLOGY: A decade-long cohort (2014-2025) was analyzed across three AJCC editions. Depth of Invasion (DOI)'s prognostic value was assessed using chi-square tests, while vermillion lip reclassification in the 9th edition was evaluated using risk ratios. Stage migration and treatment-impacting transitions were quantified using transition matrices and heatmaps. Kaplan-Meier curves with risk tables were generated to assess overall survival for the AJCC 8th and 9th editions.

RESULTS

Out of a sample size of 532 (M:F = 7:1; mean age 50.9 years, buccal mucosa (65%), tongue/floor of mouth (32.2%), and lip (2.8%), 96.8% were treatment-naïve. DOI-driven upstaging occurred in 29.3% of cases (McNemar's p < 0.001), prompting treatment escalation. Vermillion lip cancers demonstrated lower nodal metastatic risk than other oral subsites {RR 1.39 (95% CI: 0.47-4.11)}. Furthermore, regrouping vermillion lip within cutaneous malignancy demonstrated a 4- fold difference in propensity for nodal metastases between early and advanced T stage (RR = 4.0, 95% CI: 0.66-24.3; OR = 10.0, 95% CI: 0.94-106.5) endorsing its inclusion within cutaneous malignancy. The 7th-8th edition transition caused significant upstaging and treatment escalation, while the 9th edition remained stable except for marked lip tumor reclassification (p < 0.001). Kaplan-Meier analysis showed comparable overall survival, with a modest late advantage for the AJCC 9th edition.

CONCLUSION

AJCC staging evolution has progressively improved risk stratification in oral cancers. The 8th edition introduced clinically meaningful refinements, while the 9th edition maintained staging stability and optimized lip cancer classification.