Differences in Prevalence of Lymphovascular Invasion among Early Gastric Cancers between Korea and Japan

Background/Aims The presence of invasion is a diagnostic criterion of early gastric cancer (EGC) in Korea, whereas diagnosis in Japan is based on enlarged nuclei and prominent nucleoli. Moreover, the depth of invasion is the location of cancer cell infiltration in Korea, whereas it is the location of lymphovascular invasion (LVI) or cancer cell infiltration in Japan. We evaluated the characteristics of EGC with LVI to uncover the effects of different diagnostic criteria. Methods Consecutive T1-stage EGC patients who underwent complete resection were included after endoscopic or surgical resection. The presence of LVI was evaluated. Results LVI was present in 112 of 1,089 T1-stage EGC patients. LVI was associated with depth of invasion (p<0.001) and age (p=0.017). The prevalence of LVI in mucosal cancer was significantly higher in Korea (p<0.001), whereas that of submucosal cancer was higher in Japan (p=0.024). For mucosal EGC types, LVI was positively correlated with diagnostic criteria applied in Korea (p=0.017). For submucosal EGC types, LVI was positively correlated with Japanese criteria (p=0.001) and old age (p=0.045). Conclusions The higher prevalence of LVI for mucosal EGC in Korea and for submucosal EGC in Japan indicates that different diagnostic criteria should be considered when reading publications from other countries.