在进行原发性系统治疗（PST）的临床无淋巴结转移（cN0）早期乳腺癌（EBC）中，治疗后出现阳性哨兵淋巴结（SLN+）会引导腋窝淋巴结清扫（ALND），对结局产生不确定的影响并增加并发症。我们对经过PST和乳房手术导致SLN+和接受ALND的影像学确认的cN0 EBC进行了观察性研究。使用逻辑回归分析基线/术后临床病理因素与阳性非哨兵附加腋窝淋巴结（non-SLN+）之间的关联。LASSO回归确定了要包括在预测non-SLN+的评分（ALND-predict）中的变量。评估准确性和校准度，然后确定最佳切点并进行虚拟验证和自举。在ALND后，22.2%的病例中检测到non-SLN+。仅孕激素受体（PR）水平和大转移SLN+与non-SLN+独立相关。LASSO回归确定了PR，Ki67和SLN+的类型和数量作为最有效的协变量。ALND-predict评分基于它们的LASSO回归系数构建，显示出0.83的曲线下面积（AUC）和63的最佳截断值，具有0.925的负预测值（NPV）。连续和二元评分具有良好的拟合（p = 0.876和p = 1.00，分别）并且与non-SLN+独立相关（调整的比值比（aOR）：1.06，p = 0.002和aOR：23.77，p <0.001）。经过5000次自举调整后重新测试，估计的偏差校正和加速的95％CI包括aOR。在具有SLN+的cN0 EBC中，ALND中出现的non-SLN+不常见（约22％），并且与PR水平和大肿块SLN独立相关。 ALND-predict多参数评分准确地预测了non-SLN参与的情况，确定了大多数可以安全地避免不必要ALND的患者。需要进行前瞻性验证。 ©2023年作者。

In clinically node-negative (cN0) early stage breast cancer (EBC) undergoing primary systemic treatment (PST), post-treatment positive sentinel lymph node (SLN+) directs axillary lymph node dissection (ALND), with uncertain impacts on outcomes and increased morbidities.We conducted an observational study on imaging-confirmed cN0 EBC, who underwent PST and breast surgery that resulted in SLN+ and underwent ALND. The association among baseline/postsurgical clinic-pathological factors and positive nonsentinel additional axillary lymph nodes (non-SLN+) was analyzed with logistic regression. LASSO regression (LR) identified variables to include in a predictive score of non-SLN+ (ALND-predict). The accuracy and calibration were assessed, an optimal cut-point was then identified, and in silico validation with bootstrap was undertaken.Non-SLN+ were detected in 22.2% cases after ALND. Only progesterone receptor (PR) levels and macrometastatic SLN+ were independently associated to non-SLN+. LR identified PR, Ki67, and type and number of SLN+ as the most efficient covariates. The ALND-predict score was built based on their LR coefficients, showing an area under the curve (AUC) of 0.83 and an optimal cut-off of 63, with a negative predictive value (NPV) of 0.925. Continuous and dichotomic scores had a good fit (p = 0.876 and p = 1.00, respectively) and were independently associated to non-SLN+ [adjusted odds ratio (aOR): 1.06, p = 0.002 and aOR: 23.77, p < 0.001, respectively]. After 5000 bootstrap-adjusted retesting, the estimated bias-corrected and accelerated 95%CI included the aOR.In cN0 EBC with post-PST SLN+, non-SLN+ at ALND are infrequent (~22%) and independently associated to PR levels and macrometastatic SLN. ALND-predict multiparametric score accurately predicted absence of non-SLN involvement, identifying most patients who could be safely spared unnecessary ALND. Prospective validation is required.© 2023. The Author(s).