Abstract P2-01-26: Validation of a Chinese nomogram with a Dutch breast cancer population: Excellent prediction of the probability of axillary lymph node metastasis

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Abstract Background: In the era of precision medicine, the surgical management of axillary lymph nodes (ALN) should be patient-tailored. Omission of sentinel lymph node biopsy (SLNB) is possible in patients with early breast cancer and very low or very high probability of ALN metastasis. Recently, we developed a nomogram to predict the probability of ALN metastasis in breast cancer patients based on clinicopathological parameters including ultrasound using a Chinese patient dataset1. In this study the nomogram performance was validated in an independent Dutch population from one hospital. Methods: Data of 170 Dutch patients with a successful SLNB or axillary lymph node dissection were collected. A lymph node containing either micro- or macrometastatic disease was considered as a positive lymph node. Performance of the nomogram was assessed by calculating the area under the receiver-operator characteristic (ROC) curve (AUC). False-negative rates (FNRs) and false-positive rates (FPRs) at several different predictive cut-off points were calculated. Results: There were 69 (40.6%) patients having a positive ALN. The AUC for the nomogram was 0.84 (95% confidence interval 0.78-0.90) compared with 0.86 in the Chinese validation population, showing excellent discrimination of the model. The FNR and FPR of the model were 10.2% and 0% for the predicted probability cut-off points of 14.5% and 90%, respectively. Table 1 False-negative rates (FNRs) and false-positive rates (FPRs) of the nomogram at different predictive cut-off pointsPredicted rishPatient number and percentage (%)Number of patients with positive ALNFNR (%)< 14.5%59 (34.7)610.2< 20%79 (46.5)1113.9 Number of patients with negative ALNFPR (%)> 70%27 (15.9)13.7> 90%18 (10.6)00ALN: axillary lymph node This means that omission of SLNB is possible for patients with a predictive probability of less than 14.5% or higher than 90%, which accounts for 45.3% of all patients in this study. Conclusions and future perspectives: In this study, the Chinese nomogram showed excellent performance in predicting the probability of ALN metastasis in an independent Dutch population. A multicentre validation of this nomogram in large Dutch patient population (>2500 patients) is ongoing. Reference 1.Qiu S-Q, Zeng H-C, Zhang F, et al. A nomogram to predict the probability of axillary lymph node metastasis in early breast cancer patients with positive axillary ultrasound. Sci Rep 2016; 6: 21196. Citation Format: Qiu S-Q, Aarnink M, van Maaren MC, Dorrius M, Koffijberg H, van Dam GM, Siesling S. Validation of a Chinese nomogram with a Dutch breast cancer population: Excellent prediction of the probability of axillary lymph node metastasis [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-01-26.

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