Can Elective Neck Dissection for Oral Cancer Be Planned on the Basis of Depth of Invasion? Retrospective Analysis.

Abstract

The literature suggests that elective neck dissection (END) may be avoided in primaries with a depth of invasion (DOI) <3 mm. This study evaluated the accuracy of DOI in predicting nodal metastases (lymph node metastasis [LNM]) in oral squamous cell carcinoma (OSCC). In this retrospective institutional chart review, pathologic N classification (pN) was correlated with DOI using Spearman's rank-order (pN1-3) and point-biserial (pN0 <i>v</i> pN+) correlation statistics. The receiver operating characteristic (ROC) curve was analyzed to determine the accuracy of DOI in predicting LNM. Chi-square statistics were used to measure the association between the DOI groups and pN status (pN0; pN+). Post hoc analysis of variance with Bonferroni statistics was used to compare the three DOI groups. DOI failed to demonstrate a strong positive correlation with the pN classification (ρ = 0.31; <i>P</i> < .001). DOI was not strongly correlated with pN status (<i>r</i>_pb = 0.27; <i>P</i> < .001). ROC curve analysis suggested a poor accuracy of DOI in predicting nodal metastases (AUC = 0.67 [95% CI, 0.6 to 0.73]). A statistically significant difference in LNM (pN+) was found between the DOI >10 mm and DOI ≤10 mm primaries (<i>P</i> < .001 for DOI ≤5 mm; <i>P</i> = .016 for DOI >5 mm and ≤10 mm). However, the sensitivity and specificity achieved by ROC analysis for a DOI cutoff value of 10 mm in the present cohort were 69.3% and 57.9%, respectively. DOI is a poor indicator of LNM in OSCC. The decision to perform END should not be based on the tumor DOI.