Predictive value of tumor thickness for cervical lymph‐node involvement in squamous cell carcinoma of the oral cavity

Tumor thickness (TT) appears to be a strong predictor for cervical lymph-node involvement in squamous cell carcinoma of the oral cavity (OSCC), but a precise clinically optimal TT cutoff point has not been established. To address this question, the authors conducted a meta-analysis.All relevant articles were identified from MEDLINE and EMBASE as well as from cross-referenced publications cited in relevant articles. Lymph-node involvement was confirmed and identified as positive lymph-node declaration (P(LN)D) by either pathologic positivity on immediate neck dissection or by neck recurrence identified after follow-up > or = 2 years. Odds ratios (OR) were calculated to quantify the predictive value of TT. Negative predictive values (and the percentage of patients falsely predicted to not have P(LN)D [FN-P(LN)D]) were compared to determine the optimal TT cutoff point.Sixteen studies were selected from 72 potential studies, yielding a pooled total of 1136 patients. Data were examined for the following TT cutoff points: 3 mm (4 studies, 387 patients), 4 mm (9 studies, 778 patients), 5 mm (6 studies, 367 patients), and 6 mm (4 studies, 488 patients). The OR (95% CI) was 7.3 (5.3-10.1) for the overall group. The proportion of FN-P(LN)D was 5.3% (95% CI, 2.0-11.2), 4.5% (2.6-7.2), 16.6% (11.5-22.8), and 13.0% (9.7-16.9) for TT<3, <4, <5, and <6 mm, respectively. There was a statistically significant difference between the 4-mm and 5-mm TT cutoff points (P = .007).TT was a strong predictor for cervical lymph-node involvement. The optimal TT cutoff point was 4 mm.