BACKGROUND There are no clear guidelines to determine whether to perform D1 or D1+ lymph node dissection in early gastric cancer (EGC). This study aimed to develop a nomogram for estimating the risk of extraperigastric lymph node metastasis (LNM). MATERIALS AND METHODS Between 2009 and 2019, a total of 4,482 patients with pathologically confirmed T1 disease at 6 affiliated hospitals were included in this study. The basic clinicopathological characteristics of the positive and negative extraperigastric LNM groups were compared. The possible risk factors were evaluated using univariate and multivariate analyses. Based on these results, a risk prediction model was developed. A nomogram predicting extraperigastric LNM was used for internal validation. RESULTS Multivariate analyses showed that tumor size (cut-off value 3.0 cm, odds ratio [OR]=1.886, P=0.030), tumor depth (OR=1.853 for tumors with sm2 and sm3 invasion, P=0.010), cross-sectional location (OR=0.490 for tumors located on the greater curvature, P=0.0303), differentiation (OR=0.584 for differentiated tumors, P=0.0070), and lymphovascular invasion (OR=11.125, P<0.001) are possible risk factors for extraperigastric LNM. An equation for estimating the risk of extraperigastric LNM was derived from these risk factors. The equation was internally validated by comparing the actual metastatic rate with the predicted rate, which showed good agreement. CONCLUSIONS A nomogram for estimating the risk of extraperigastric LNM in EGC was successfully developed. Although there are some limitations to applying this model because it was developed based on pathological data, it can be optimally adapted for patients who require curative gastrectomy after endoscopic submucosal dissection.

中文翻译：

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预测早期胃癌患者腹外淋巴结转移的列线图。

背景 没有明确的指南来确定是否在早期胃癌 (EGC) 中进行 D1 或 D1+ 淋巴结清扫。本研究旨在开发列线图来估计胃外淋巴结转移 (LNM) 的风险。材料与方法 2009年至2019年，本研究共纳入6家附属医院经病理证实的T1期疾病患者4482例。比较阳性和阴性腹外LNM组的基本临床病理学特征。使用单变量和多变量分析评估可能的危险因素。基于这些结果，开发了风险预测模型。预测腹外 LNM 的列线图用于内部验证。结果 多变量分析显示肿瘤大小（临界值 3.0 cm，比值比 [OR] = 1.886，P=0.030）、肿瘤深度（对于sm2和sm3浸润的肿瘤OR=1.853，P=0.010）、横截面位置（对于位于大弯侧的肿瘤OR=0.490，P=0.0303）、分化（OR=0.584对于分化型肿瘤，P=0.0070）和淋巴血管浸润（OR=11.125，P<0.001）是腹外 LNM 的可能危险因素。从这些风险因素中推导出用于估计腹外 LNM 风险的方程式。通过将实际转移率与预测率进行比较，该方程得到了内部验证，结果显示出良好的一致性。结论 成功开发了用于估计 EGC 腹外 LNM 风险的列线图。尽管由于该模型是根据病理数据开发的，因此应用该模型存在一些局限性，