Background: It was the aim of our study to establish a model for prediction of lymph node metastases in superficial esophageal cancer.
Methods: We analyzed the clinical and histopathological data of 50 consecutive patients with pT1-esophageal cancer who underwent oncological resection. Submucosal carcinomas (pT1b) were classified according to sm levels 1-3. D2-40 immunostaining was investigated using the ABC technique. In a first step, we performed univariate analysis (One-way ANOVA: Sigma restricted parameterization; test of SS whole vs. SS predicted) to test the predictive value of the following categorical parameters for lymph node status (positive/negative): sex, histologic tumor type, localization, surgical technique (transhiatal/transthoracic), grading, pT1-subclassification (pT1a, pT1b sm 1-3), pL-, pV-status, and D2-40 labeling. Simple regression was applied for the following continuous predictors: age and tumor size. All significant variables of univariate analysis were included in the multivariate analysis. For this purpose, we used the General Liner Models's analysis (forward stepwise). In a third step, the Kruskal-Wallis test with post hoc comparisons was intended to define the cut-off value of parameters tested.
Results: Only the following variables gained statistical significance in univariate analysis: sex, histological tumor type, grading, pT1-subclassification, lymphatic infiltration, microvascular infiltration, D2-40 immunostaining, and tumor size (P < 0.05). Variables reaching significance in multivariate analysis were tumor size (P = 0.017) and pV-status (P = 0.037). In the Kruskal-Wallis test with post hoc comparisons, the cut-off value of tumor size was 2 cm (model P = 0.002) and between the categories (P < 0.05).
Conclusions: Lymph node positivity and lymphatic vessel infiltration did not linearly increase with sm tumor infiltration depth. The risk category of lymph node involvement in superficial esophageal cancer exists according to our prediction model on the basis of tumor size of >2 cm and microvascular infiltration. The hitherto common sm levels 1-3 classification of submucosal cancers appears to display a lesser impact than previously assumed with regard to prediction of potential lymph node metastases and consequently the indication for endoscopic or surgical therapy.