The longest diameter of tumor as a parameter of endoscopic resection in early gastric cancer: In comparison with tumor area

Background and aim Tumor burden is important to predict clinical behaviors of cancer such as lymph node metastasis (LNM). Tumor size has been used as a parameter of tumor burden such as indication of endoscopic resection in early gastric cancer (EGC) to predict LNM. Thus, we aimed to investigate whether tumor area can be more helpful to predict clinical behaviors than longest diameter of tumor in EGC. Patients and methods 3,059 patients who underwent gastrectomy for EGC were reviewed retrospectively. Tumor area was calculated by multiplying long and short diameter of the tumor in surgical specimen. Longest diameter means maximal longitudinal diameter of tumor in specimen. Clinicopathologic features were compared between longest diameter and area using area under receiver operating characteristic (AUROC) curves. Results Longest diameter and area of tumor showed a strong correlation (correlation coefficient 0.859, p<0.01). The cutoff value for prediction of LNM was 20 mm of longest diameter of tumor and 270 mm² of tumor area. There was no significant difference between longest diameter and area for prediction of LNM (AUC 0.850 vs. 0.848, respectively). In differentiated-type EGC and undifferentiated-type EGC, there was no significant difference between longest diameter and area for prediction of LNM. Among mucosal or submucosal cancer prediction value of LNM between longest diameter and area was not significantly different. Conclusion Tumor area may not be more helpful to predict LNM than longest diameter in EGC. Therefore, the longest diameter of tumor may be sufficient as an indicator of tumor burden in EGC.