Punch Biopsy for Preoperative Depth of Invasion Assessment in Early Oral Tongue Squamous Cell Carcinoma: A Prospective Pilot Study

ImportanceThe inclusion of depth of invasion (DOI) in the American Joint Committee on Cancer's staging system for oral tongue squamous cell carcinoma (OTSCC) has major clinical implications. Few studies have evaluated the accuracy of preoperative biopsy to predict DOI.ObjectiveTo evaluate the reliability of preoperative punch biopsy for measuring DOI in early OTSCC and compare it to evaluation by digital palpation. Secondarily, to assess the punch biopsy's ability to differentiate between carcinoma in situ (Tis) and invasive carcinoma.DesignA prospective single-center cohort study.SettingCenter Hospitalier de l'Université de Montréal, a tertiary center in Canada.ParticipantsPatients with suspected early stage OTSCC.InterventionPunch biopsy was used to sample the deepest part of tumors to measure biopsy-derived DOI (bDOI). In addition, DOI was estimated via digital palpation: clinical DOI (cDOI) by surgeons.Main Outcome MeasuresPathologic DOI (pDOI) from final histopathology reports was the gold standard. Spearman's correlations were calculated between cDOI, bDOI, and pDOI. Diagnostic performance metrics were calculated for the ability to distinguish pDOI of ≥2 mm, and to differentiate Tis from invasive carcinoma.ResultsAmong 27 patients, correlation coefficients between bDOI and pDOI, and cDOI and pDOI were 0.603 (95% CI: 0.202-0.884) and 0.894 (95% CI: 0.749-0.955), respectively. Punch biopsy sensitivity and specificity were 0.88 (95% CI: 0.62-0.98) and 0.91 (95% CI: 0.59-0.99) to detect pDOI ≥ 2 mm, and 0.89 (95% CI: 0.65-0.99) and 0.86 (95% CI: 0.42-1.00) for distinguishing Tis from invasive carcinoma. Digital palpation sensitivity and specificity for pDOI ≥ 2 mm were 0.86 (95% CI: 0.57-0.98) and 1.00 (95% CI: 0.63-1.00).ConclusionsPunch biopsy and clinical palpation demonstrate high diagnostic yield for identifying lesions with pDOI ≥ 2 mm. Punch biopsy appears to be reliable to distinguish Tis from invasive carcinoma.RelevanceLarger studies are needed to corroborate these findings and assess the role of punch biopsy in guiding elective neck dissection decisions.