Tumour growth kinetics and stage progression during treatment delay in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) frequently progresses during delays before definitive treatment, yet the biological behavior of tumours during this interval remains poorly characterized. We prospectively evaluated tumour growth kinetics, stage progression, and anatomic pathways of spread using serial pre-treatment imaging.

This prospective observational study included 483 patients with treatment-naïve OSCC treated between July 2020 and December 2023. Eligible patients underwent at least two clinically indicated pre-treatment imaging studies separated by ≥ 3 weeks. Gross tumour volume (GTV), tumour volume doubling time (TVDT), stage progression, and subsite-specific spread patterns were analyzed and correlated with survival outcomes.

The median interval between serial imaging studies was 7.1 weeks. Median tumour volume increased from 12.9 cm³ to 19.4 cm³, corresponding to a median growth rate of 7.3% per week and a median TVDT of 7.9 weeks. Stage progression occurred in 30% of patients, while nodal progression was observed in 23%. Tongue tumours demonstrated predominantly longitudinal spread, buccal tumours extended laterally and posteriorly, alveolar tumours showed early bone invasion, and retromolar trigone tumours preferentially invaded deep spaces. Patients with TVDT ≤ 8 weeks demonstrated significantly worse survival.

OSCC demonstrates rapid progression during untreated intervals and follows reproducible subsite-specific pathways of spread.