Correlation between clinical and MRI assessment of depth of invasion in oral tongue squamous cell carcinoma

Background: Neck metastasis is the most important prognostic factor in oral cavity squamous cell carcinomas (SCC). Apart from the T-stage, depth of invasion has been used as a highly predictable factor for microscopic neck metastasis, despite the controversy on the exact depth cut off point. Depth of invasion can be determined clinically and radio logically. However, there is no standard tool to determine depth of invasion preoperatively. Although MRI is used widely to stage the head and neck disease, its utility in depth evaluation has not formally been assessed. Objective: To compare preoperative clinical and radiological depth evaluation in oral tongue SCC using the standard pathological depth. To compare clinical and radiological accuracy between superficial (< 5 mm) vs. deep invaded tumor (>= 5 mm) Methods: This prospective study used consecutive biopsy-proven oral tongue invasive SCC that presented to the University health network (UHN), Toronto. Clinical examination, radiological scan and appropriate staging were determined preoperatively. Standard pathology reports postoperatively were reviewed to determine the depth of invasion from the tumor specimen. Results: 72 tumour samples were available for analysis and 53 patients were included. For all tumors, both clinical depth (r = 0.779; p < 0.001) and radiographic depth (r = 0.907; p < 0.001) correlated well with pathological depth, with radiographic depth correlating slightly better. Clinical depth also correlated well with radiographic depth (r = 0.731; p < 0.001). By contrast, for superficial tumors (less than 5 mm on pathological measurement) neither clinical (r = 0.333, p = 0.34) nor radiographic examination (r = -0.211; p = 0.56) correlated with pathological depth of invasion. Conclusion: This is the first study evaluating the clinical assessment of tumor thickness in comparison to radiographic interpretation in oral cavity cancer. There are strong correlations between pathological, radiological, and clinical measurements in deep tumors (>= 5 mm). In superficial tumors (< 5 mm), clinical and radiological examination had low correlation with pathological thickness.