Objective: Depth of invasion (DOI) has been incorporated in the new AJCC 8th classification. However, even with this new AJCC classification stage III oral tongue squamous cell carcinoma (OTSCC) remains a heterogenous group. The study aims at finding a discreet group within stage III using DOI as a cut-off of 10 mm.
Methods: The institutional database was reviewed from 2012 to 2018 for postoperative stage III OTSCC patients who subsequently received postoperative radiotherapy. Ninety-six patients matched the inclusion criteria. Two groups were created using a DOI cut-off of 10 mm (superficial and deep groups). The groups were analyzed for overall survival (OS) and relapse-free survival (RFS).
Results: The baseline and treatment characteristics were comparable between the groups except for the higher number of extensive surgeries, endophytic configuration, pT3 and, DOI in the deep group. For a median follow-up of 40.5 (range: 4-139) months, the median OS and RFS for the superficial group were not reached. The median OS and RFS for the deep group were 101 (range: 73.7-128.3) and 60 (range: 46.6-73.4) months, respectively. The difference was statistically significant for median RFS (P = .008) and trended toward significance for median OS (P = .066) for the superficial group. Multivariate Cox regression analysis showed DOI cut-off as a significant predictor for RFS but not for OS.
Conclusion: DOI significantly predicts poor RFS. However, showed a trend toward poor OS. This study hints toward a possibility of sub-dividing stage III OTSCC based on DOI cut-off.
Level of evidence: 3 (Retrospective cohort study) Laryngoscope, 132:1594-1599, 2022.
Keywords: Oral cavity tumors; depth of invasion; radiation; surgery; tongue cancer.
© 2021 The American Laryngological, Rhinological and Otological Society, Inc.