Purpose

Residual lymph node metastases (RLNM) remained a great concern in the implementation of organ-preserving strategies and led to poor prognosis in locally advanced rectal cancer (LARC). In this study, we aimed to identify the clinicopathological factors correlated with RLNM in LARC patients with ypT0-2 after neoadjuvant chemoradiotherapy (NCRT).

Methods

We retrospectively analyzed 417 patients histologically diagnosed middle-low LARC after NCRT and total mesorectal excision (TME), whose pathological staging was ypT0-2. All patients received pelvic magnetic resonance imaging (MRI) before NCRT. The radiation doses were 50–50.6 Gy for the planning gross tumor volume and 41.8–45 Gy for the planning target volume, respectively. A nomogram for predicting RLNM was constructed using a binary logistic regression. Nomogram performance was assessed by receiver operating characteristic (ROC) curve, calibration curve, decision curve analysis (DCA) and clinical impact curve (CIC).

Results

After surgery, 191 patients (45.8%) were ypT0, 43 patients (10.3%) were ypT1 and 183 patients (43.9%) were ypT2, and a total of 49 patients (11.8%) were found the presence of RLNM. Multivariable analyses identified MRI-defined mesorectal fascia (MRF)-positive, high-grade histopathology at biopsy, advanced ypT-category, and the presence of perineural invasion (PNI) as the predictive factors. The nomogram, incorporating all these predictors, showed good discrimination and calibration efficacy, with the areas under the ROC curve of 0.690 (95% CI: 0.610–0.771). Both DCA and CIC demonstrated that this nomogram has good clinical usefulness.

Conclusion

The nomogram model can predict RLNM in patients with ypT0-2 tumors. It can help select suitable patients for performing organ-preserving strategies after NCRT.

中文翻译：

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临床病理因素预测ypT0-2局部晚期直肠癌新辅助放化疗后残余淋巴结转移

目的

残余淋巴结转移（RLNM）仍然是器官保留策略实施中的一个重要问题，并导致局部晚期直肠癌（LARC）预后不良。在本研究中，我们旨在确定新辅助放化疗（NCRT）后 ypT0-2 的 LARC 患者中与 RLNM 相关的临床病理因素。

方法

我们回顾性分析了417例经NCRT和全直肠系膜切除术（TME）后组织学诊断为中低LARC的患者，其病理分期为ypT0-2。所有患者在 NCRT 前均接受盆腔磁共振成像 (MRI)。计划总肿瘤体积的辐射剂量为 50-50.6 Gy，计划靶体积的辐射剂量为 41.8-45 Gy。使用二元逻辑回归构建了用于预测 RLNM 的列线图。通过受试者工作特征（ROC）曲线、校准曲线、决策曲线分析（DCA）和临床影响曲线（CIC）评估列线图性能。

结果

术后，191例（45.8%）为ypT0，43例（10.3%）为ypT1，183例（43.9%）为ypT2，共有49例（11.8%）患者发现存在RLNM。多变量分析确定 MRI 定义的直肠系膜筋膜 (MRF) 阳性、活检时的高级别组织病理学、晚期 ypT 类别以及神经周围侵犯 (PNI) 的存在作为预测因素。包含所有这些预测因素的列线图显示出良好的区分和校准功效，ROC 曲线下面积为 0.690（95% CI：0.610-0.771）。 DCA和CIC均证明该列线图具有良好的临床实用性。

结论

列线图模型可以预测 ypT0-2 肿瘤患者的 RLNM。它可以帮助选择合适的患者在 NCRT 后实施器官保留策略。