根治性睾丸切除术后接受监测的临床 I 期 (CSI) 睾丸精原细胞瘤 (SGCTT) 患者的复发率为 4-30%，具体取决于肿瘤大小和睾丸网侵犯 (RTI)。然而，支持在临床决策中使用这两种风险因素的证据水平较低。我们的目的是确定 CSI SGCTT 患者复发的最重要的预后因素。1994 年至 2019 年间诊断的 1016 名 CSI SGCTT 患者的个体患者数据从九个机构收集了睾丸切除术后血清肿瘤标志物水平正常并接受监测的患者。多变量 Cox 比例风险回归模型适合确定最重要的预后因素。主要终点是通过影像学和/或标记物检测到首次复发的时间。复发概率通过 Kaplan-Meier 方法估计。中位随访 7.7 年后，149 名 (14.7%) 患者复发。根据肿瘤大小（≤2、>2-5 和 >5 cm）、是否存在 RTI 和淋巴管侵犯来形成三个风险组：低风险组 (56.4%)、中风险组 (41.3%) 和高风险组 (2.3%) ) 5 年累积复发概率分别为 8%、20% 和 44% 的风险。该模型优于当前使用的模型，肿瘤大小 ≤4 与 >4 cm 且存在 RTI（Harrell 的 C 指数 0.65 与 0.61）。低风险和中风险组在由 285 名患者组成的独立队列中得到了成功验证。接受监测的 CSI SGCTT 患者根治性睾丸切除术后复发的风险较低。我们提出了一种新的风险分层模型，该模型优于当前模型，并确定了具有高复发风险的小亚组。临床 I 期睾丸精原细胞瘤患者进行根治性睾丸切除术后复发的风险较低。我们提出了一种新的风险分层模型，该模型优于当前模型，并确定了具有高复发风险的小亚组。版权所有 © 2023。由 Elsevier B.V. 出版。

The relapse rate in patients with clinical stage I (CSI) seminomatous germ cell tumor of the testis (SGCTT) who were undergoing surveillance after radical orchidectomy is 4-30%, depending on tumor size and rete testis invasion (RTI). However, the level of evidence supporting the use of both risk factors in clinical decision-making is low.We aimed to identify the most important prognostic factors for relapse in CSI SGCTT patients.Individual patient data for 1016 CSI SGCTT patients diagnosed between 1994 and 2019 with normal postorchidectomy serum tumor marker levels and undergoing surveillance were collected from nine institutions.Multivariable Cox proportional hazard regression models were fit to identify the most important prognostic factors. The primary endpoint was the time to first relapse by imaging and/or markers. Relapse probabilities were estimated by the Kaplan-Meier method.After a median follow-up of 7.7 yr, 149 (14.7%) patients had relapsed. Categorical tumor size (≤2, >2-5, and >5 cm), presence of RTI, and lymphovascular invasion were used to form three risk groups: low (56.4%), intermediate (41.3%), and high (2.3%) risks with 5-yr cumulative relapse probabilities of 8%, 20%, and 44%, respectively. The model outperformed the currently used model with tumor size ≤4 versus >4 cm and presence of RTI (Harrell's C index 0.65 vs 0.61). The low- and intermediate-risk groups were validated successfully in an independent cohort of 285 patients.The risk of relapse after radical orchidectomy in CSI SGCTT patients under surveillance is low. We propose a new risk stratification model that outperformed the current model and identified a small subgroup with a high risk of relapse.The risk of relapse after radical orchidectomy in patients with clinical stage I seminomatous germ cell tumor of the testis is low. We propose a new risk stratification model that outperformed the current model and identified a small subgroup with a high risk of relapse.Copyright © 2023. Published by Elsevier B.V.