Preoperative evaluation of depth of invasion in oral tongue squamous cell carcinoma: A systematic review and meta-analysis

The inclusion of depth of invasion (DOI) in the American Joint Committee on Cancer's staging system for oral cavity squamous cell carcinoma (SCC) has major clinical impacts. Recent studies have evaluated the reliability of imaging modalities and biopsy techniques to measure DOI preoperatively. The objective of this systematic review and meta-analysis was to comprehensively include all previously described methods to measure preoperative DOI in oral tongue SCC (OTSCC) and to compare their reliability. A systematic review was conducted on PubMed, Embase and Cochrane according to the PRISMA guidelines. Studies that evaluated the reliability of DOI measured on biopsy or imaging (rDOI) by comparing it to DOI on histopathology (pDOI) were included for extraction. A meta-analysis was conducted to obtain pooled correlation coefficients for each imaging modality. The pooled correlation coefficients between rDOI and pDOI were 0.86 (CI95% = [0.82-0.88]) and 0.80 (CI95% = [0.70-0.87]) for magnetic resonance imaging (MRI) studies and computed tomography (CT) studies, respec-tively. For ultrasound (US), the correlation coefficient could only be measured by including studies which measured not only DOI but also tumor thickness. It was 0.89 (CI95%= [0.82-0.94]). Overall, MRI is the better studied modality. It has a good reliability to measure preoperative rDOI in OTSCC. CT is less studied but appears to be less reliable. US cannot be compared to these imaging modality as it has been used more often to measure TT than DOI.