下肢结节性黑色素瘤（NM）是一种常见的恶性肿瘤，预后较差。我们的目标是确定预后因素并开发列线图模型来预测下肢 NM 患者的总生存期 (OS)。从监测、流行病学和最终结果（SEER）数据库中选取 746 例下肢 NM 患者并随机分为训练集（522 例）和验证集（224 例）。训练集经过单变量和多变量 Cox 回归分析，以确定与患者结果相关的独立预后因素，并开发列线图模型。随后使用验证集验证列线图的有效性。训练集的多变量 Cox 回归分析表明，年龄、溃疡、放疗、化疗、首次恶性肿瘤的原发部位和 Breslow 厚度是与 OS 相关的自变量。在训练集中，预测 3 年和 5 年 OS 的列线图的曲线下面积 (AUC) 分别为 0.796 和 0.811。在验证集中，预测 3 年和 5 年 OS 的 AUC 分别为 0.694 和 0.702。训练集和验证集的 Harrell C 指数分别为 0.754 (95% CI: 0.721-0.787) 和 0.670 (95% CI: 0.607-0.733)。训练集和验证集的校准曲线显示出良好的一致性。在本研究中，我们开发并验证了列线图来预测下肢 NM 患者的 OS。列线图显示了合理的可靠性和临床适用性。列线图是评估预后和帮助临床决策的重要工具。© 2024。作者获得 Springer-Verlag GmbH 德国（Springer Nature 旗下公司）的独家许可。

Lower extremity nodular melanoma (NM) is a common malignant tumor with a poor prognosis. We aims to identify the prognostic factors and develop a nomogram model to predict overall survival (OS) in patients with lower extremity NM. A total of 746 patients with lower extremity NM were selected and randomly divided into a training set (522 cases) and a validation set (224 cases) from the Surveillance, Epidemiology, and End Results(SEER) database. The training set underwent univariate and multivariate Cox regression analyses to identify independent prognostic factors associated with patient outcomes, and to develop a nomogram model. The effectiveness of the nomogram was subsequently validated using the validation set. Multivariable Cox regression analysis of the training set indicated that age, ulceration, radiotherapy, chemotherapy, primary site of first malignant tumor, and Breslow thickness were independent variables associated with OS. In the training set, the area under the curve (AUC) of the nomogram for predicting 3-year and 5-year OS was 0.796 and 0.811, respectively. In the validation set, the AUC for predicting 3-year and 5-year OS was 0.694 and 0.702, respectively. The Harrell's C-index for the training set and validation set were 0.754 (95% CI: 0.721-0.787) and 0.670 (95% CI: 0.607-0.733), respectively. Calibration curves for both training and validation sets showed good agreement. In this study, we develop and validate a nomogram to predict OS in patients with lower extremity NM. The nomogram demonstrated reasonable reliability and clinical applicability. Nomograms are important tools assessing prognosis and aiding clinical decision-making.© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.