A Proposal for Grading the Risk of Lymph Node Metastasis After Noncurative Endoscopic Resection for Early Gastric Cancer

<i>Background</i>Gastrectomy with lymphadenectomy is the standard of care for noncurative endoscopic resection (ER) (endoscopic curability C2; eCuraC2) for early gastric cancer (EGC); however, this strategy may be excessive for most patients because few patients have lymph node metastasis (LNM). In addition, whether EGCs with undifferentiated components (undiff-components) in the eCuraA group are suitable for ER remains controversial. The aim of this study was to stratify the eCuraC2 group according to LNM risk, and to verify the safety of conservative treatment for patients with undiff-components of the eCuraA group.<i>Methods</i>We retrospectively analyzed 272 patients with submucosal invasion or with undiff-components who underwent initial ER for EGC. These specimens were classified into eCura A, B, C1, and C2 groups according to the Japanese Gastric Cancer Association (JGCA) guidelines, and the rate of LNM in each group was analyzed. The key risk factors were identified by analyzing the correlation between different combinations of risk factors and LNM, and according to the LNM risk, further graded the eCuraC2 group.<i>Results</i>Among the 162 eCuraC2 patients, 9 (5.6%) had LNM. But no patients in the other groups, including all 57 patients of the eCuraA group (T1a, < 2 cm in diameter and no ulceration) with undiff-components, had LNM. A tumor diameter >3 cm (1.7% vs 12.2%, <i>P</i> = .005), positive for vertical margins (1.6% vs 20.0%, <i>P</i> < .001), submucosal invasion (≥500 μm) (0.7% vs 6.6%, <i>P</i> = .012), undiff-components type dominance (0% vs 11.9%, <i>P</i> < .001) and lymphovascular infiltration (LVI) (1.3% vs 16.7%, <i>P</i> < .001) were significantly correlated with LNM. When the patients in the eCuraC2 group were divided into 4 groups based on the presence of LVI and undiff-components, the LNM rate in each group was 0/81 patients (0%) in the LVI (-) undiff-components (-) group, 3/45 patients (6.7%) in the LVI (-) undiff-components (+) group, 0/15 patients (0%) in the LVI (+) undiff-components (-) group, and 6/21 patients (28.6%) in the LVI (+) undiff-components (+) group. Finally, based on these 2 factors, eCura C2 patients were classified into 3 LNM risk grades: low (LVI (-) undiff-components (-), LNM 0%), intermediate (LVI (+) or undiff-components (+), LNM 5%), and high (LVI (+) undiff-components (+), LNM 28.6%).<i>Conclusion</i>Based on LVI and histological differentiation, eCuraC2 patients were classified into 3 LNM risk grades, and approximately half of the eCuraC2 patients were reclassified into the low-risk group. No LNM was found in patients in the eCuraA group with undiff-components.