Radiological tumor thickness as a clinical predictor of pathological depth of invasion in oral squamous cell carcinoma: a retrospective analysis.

Purpose: Inclusion of depth of invasion (DOI) in the recent AJCC/UICC TNM staging for oral cancer has incorporated the concept of tumor third dimension and its prognostic importance. However, there is no uniform consensus about measuring DOI at clinical setting at present. For more practical reasons, radiological tumor thickness (rTT) is a simple and practical measurement which can be used as a clinical predictor of pDOI.

Methods: We compared rTT and pathological DOI (pDOI) of 179 patients with OSCC who underwent curative surgery from April 2018 to April 2020 at AIIMS Rishikesh, India. Spearman correlation was used to determine correlation between rTT and pDOI. ROC curve was used to determine inter-group cutoff values.

Results: Overall, rTT showed a strong correlation with pDOI (rho = 0.74; 95% CI 0.667-0.8; p < 0.001). The inter-group cutoff value for rTT were 8 mm (Sn 89.1%; Sp 53.2%) between Group A (pDOI ≤ 5 mm) and B (pDOI > 5 mm, ≤ 10 mm), and 14 mm (Sn 89.5%; Sp 78.3%) between Group B and C (pDOI > 10 mm), respectively.

Conclusions: rTT is a clinical predictor of pDOI in OSCC, and may be considered as a surrogate of DOI in the clinical setting.