Risk stratification by degree of lymphatic invasion in patients with early gastric cancer: additional gastrectomy might not be required.

[BACKGROUND] Lymphatic invasion (LI) is a significant risk factor for lymph node metastasis (LNM) following endoscopic submucosal dissection (ESD). Nevertheless, only some cases of early gastric cancer with LI exhibit LNM. This study aimed to compare the incidence of LNM based on the degree of LI.

[METHODS] A retrospective analysis was conducted on 5032 patients who underwent ESD at Samsung Medical Center between January 2000 and January 2024. A total of 420 patients had specific data on the degree of LI in ESD specimens. LNM of 347 patients who underwent additional gastrectomy (AG) was analyzed according to the categorized three groups: Ly-s (LI in a single focus), Ly-i (two or three foci), and Ly-m (more than three foci).

[RESULTS] The Ly-s patients exhibited no LNM, whereas Ly-i and Ly-m demonstrated LNM in 11 cases (11/141, 7.8%) and 22 cases (22/112, 19.6%). Multivariable analysis revealed that Ly-m was significantly associated with LNM (ref, Ly-s; Ly-m, OR 28.09, 95% CI 1.95 - 405.32, P = 0.014). Survival analysis indicated no recurrences in the observation group of Ly-s, while the Ly-i and Ly-m observation groups experienced more recurrences than the treated (AG) groups (5-year disease-free survival; Ly-i: AG 99.3% vs. observation 81.4%, P = 0.144 and Ly-m: AG 99.1% vs. observation 60.3%, P = 0.012).

[CONCLUSIONS] The absence of LNM in patients with a single focus of LI suggests that AG might be unnecessary in these cases. Further standardization of LI assessment criteria and larger sample sizes are needed to confirm these findings.