Abstract P3-07-04: A dedicated nomogram to predict nodal pathological complete response in node-positive breast cancer patients undergoing neoadjuvant chemotherapy
Authors: Corsi Fabio , Forlini Valentina , Bossi Daniela , Albasini Sara , Truffi Marta , Sorrentino Luca 
Published: March 2020

Abstract
Background and rationale In breast cancer patients with nodal metastases at presentation, neoadjuvant chemotherapy (NAC) may downstage axillary disease. Until a few years ago, axillary lymph node dissection (ALND) has been the standard of care for node positive disease, irrespective of nodal status after completion of NAC. However, nodal pathologic complete response (pCR) is well documented in about 40-70% of women presenting with cN+ status at baseline. In this subset of patiens, ALND is therefore unnecessary. Sentinel lymph node (SLN) biopsy is accepted as a staging procedure for clinically node negative patients at baseline. Recent trials have assessed the feasibility of SLN biopsy also for patients who had clinical conversion of nodal status from cN+ to ycN0, if at least three SLNs are retrieved. However, a higher false-negative rate is the major point of controversy about adoption of SLN biopsy in these patients. A preoperative predictive model, able to assess the likelihood of axillary pCR after NAC, could help to select those patients who might be suitable candidates for SLN surgery. This approach could provide reliable nodal staging information, avoiding unjustified ALNDs and associated morbidities. Methods A retrospective review of all node-positive breast cancer patients treated by NAC between November 2000 and April 2019 at the Breast Unit of IRCCS Maugeri Hospital was performed. Patients were considered as cN+ in case of palpable axillary lymph nodes and/or suspicious lymphadenopathy on ultrasound and/or biopsy-proven nodal metastasis. After NAC completion, all patients have been treated by ALND. Baseline pre-NAC and post-NAC variables were collected and analyzed in a multivariate analysis to find predictors of axillary pCR. Identified predictors were included to develop a dedicated nomogram. Results A total of 371 clinically node-positive patients were identified. Axillary pCR (ypN0 status) was achieved in 142 patients (38%). In multivariate analysis, post-NAC clinical N stage (ycN0 vs ycN+, OR 4.61, 95%CI 2.73-7.78, p&lt;0.0001), biomolecular subtype (for triple-negative breast cancer: OR 4.36, 95%CI 1.45-13.15, p=0.009; for ER+/HER2+: OR 3.68, 95%CI 1.86-7.3, p=0.0002; for ER-/HER2+: OR 3.03, 95%CI 1.06-8.62, p=0.038)-) and clinical complete response on the breast assessed on ultrasound (OR 2.26, 95%CI 1.11-4.59, p=0.024) resulted to be the strongest indipendent predictors of axillary pCR. Based on statistical findings and clinically relevant factors, a nomogram for prediction of pCR after NAC was developed and included the above-mentioned variables and Ki67, grading and pre-NAC clinical T stage. The developed model demonstrated a good discrimination capacity (AUC: 0.77). Conclusions The developed nomogram could help to identify, among patiens cN+ at time of diagnosis, those more likely to achieve nodal pCR after completing NAC. In clinical practice, this tool could contribute to select suitable cadidates for SLN biopsy, preventing them from unnecessary ALND.
Citation Format: Fabio Corsi, Valentina Forlini, Daniela Bossi, Sara Albasini, Marta Truffi, Luca Sorrentino. A dedicated nomogram to predict nodal pathological complete response in node-positive breast cancer patients undergoing neoadjuvant chemotherapy [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-07-04.