Predicting nonsentinel lymph node metastases using established nomograms among patients with breast cancer after primary systemic therapy (PST): The transSENTINA substudy.

Abstract

1020 Background: Recent studies such as the SENTINA trial suggest that performing SLNB in patients with a cN1 status before but converting to a ycN0 status through PST result more often in a false-negative evaluation of LN status compared to SLNB at primary surgery. Therefore, there is a need to predict non-SLN status after PST and tailor axillary staging procedures. We investigated the accuracy of established nomograms to predict non-SLN metastases at primary surgery in patients after PST. Methods: The SENTINA trial is a 4-arm prospective multicenter cohort study evaluating an algorithm for the timing of a standardized SLNB in patients undergoing PST. 1,737 pts. from 104 institutions were categorized into four treatment arms according to the clinical axillary staging (including ultrasound examination) before and after chemotherapy. Patients in arm C with a cN1 status prior to PST converting to a ycN0 status but found to have a histologically positive SLN after PST were included. Several published nomograms predicting non-SLN status in patients with a positive SLN at primary surgery were applied (including the MSKCC-, Mayo-, Cambridge-, and Stanford-Nomogram, MDA-Score and Tenon-Score) and Area-under-the-Curve-(AUC)-values were calculated. Results:This subgroup comprised 592 patients. Among these, 74 patients had a positive SLN after PST and had all available data to run the nomograms. AUC-values were: MSKCC: 82.3 (95% confidence interval (95%CI) 72.6-91.9), Mayo: 71.8 (95%CI 60.1-83.5), Cambridge: 71.5 (95%CI 59.7-83.2), Stanford 70.6 (95%CI 59.7-83.2), MDA 70.7 (95%CI 59.0-82.5), and Tenon 73.1 (61.5-84.7). Conclusions: Analysis of the above nomograms in the post-neoadjuvant setting yielded AUC values comparable to those in the setting of primary surgery. Our results suggest that nomograms predicting non-SLN status in the setting of primary surgery (and particularly the MSKCC nomogram) may be used to avoid full axillary dissection in patients after PST.