Abstract PO4-02-10: Predictive Factors of Nodal Upstaging at Time of Surgery in Clinically Node Negative Patients Undergoing Neoadjuvant Chemotherapy
Authors: Melissa Rangel , Alexieva Julia , Coogan Alison , Marcus Elizabeth , Wecsler Julie 
Published: May 2024

Abstract
Introduction: Neoadjuvant chemotherapy (NAC) can be given with the intent of downstaging breast cancer or to provide prognostic information prior to any surgical intervention in both node negative (N0) and node positive patients (pts). Residual nodal disease following neoadjuvant chemotherapy generally indicates poorer overall prognosis relative to those who are node negative. Several risk factors have been postulated to predict the presence of occult lymph node metastasis: age at diagnosis, tumor size, status of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor (HER-2), and BMI. NAC has been shown to eradicate axillary lymph node metastasis in up to 40% of pts. This study aims to evaluate characteristics of clinically N0 pts who underwent NAC and were upstaged to node positive status at the time of surgery. We hope to identify patient related factors that may help predict the presence of occult nodal disease as well compare pathological complete response rate (PCR) in the breast between N0 and patients who were upstaged.
Methods: Data was collected through retrospective chart review of the Stroger Cook County electronic medical records system (CERNER). Pts treated at John H. Stroger Hospital from 2017-2021 with a new diagnosis of cT2-T3 invasive breast cancer who were clinically and radiologically node negative and received NAC were included. We compared demographic data, staging information, cancer characteristics and pathologic complete response rates (PCR) in the breast between those who remained node negative and those who had positive sentinel lymph nodes at the time of surgery. Pts with prior breast cancer diagnosis and those who underwent treatments at an outside institution were excluded. Statistical analysis included 2-tailed t-test and 2-tailed fisher’s (p&lt; 0.05).
Results: A total of 98 pts were identified, 62 with complete data for analysis,11 were upstaged at the time of surgery. When comparing pts who had nodal upstaging to those that remained node negative at time of surgery there was no significant difference between average BMI (28.5), age of diagnosis (58 years). Most pts (73%) were T2 at presentation, of those with nodal upstaging at time of surgery, 20% were T3 or higher, while only 5% of those who were not upstaged at surgery were greater than T3 (NS). Upstaged pts had an average tumor size of 4.16 cm while non-upstaged on average were 2.85 cm (P&lt; 0.01). ER positive pts (ER+) and PR positive (PR+) were more likely to have nodal upstaging post op (P&lt; 0.0012, P&lt; 0.0013) when compared to ER negative (ER-) and PR negative (PR-) respectively. The distribution of receptor status was significantly different between groups, the most common receptor status in upstaged patients was triple positive (63%) while triple negative was most common in non-upstaged (41%). Triple positive pts were more likely to be upstaged than those with other receptor statuses (64% vs 40%, p 0.0004). There was a 100% PCR rate in the breast among non-upstaged pts compared to 10% of upstaged patients (P&lt; 0.0001). Among all triple negative pts, 42% had PCR, of ER-/PR-/HER2+, 60% had a PCR, ER+/HER 2 negative had a 40% PCR.
Conclusion: Pts with larger presenting tumor size who are node negative at presentation and have undergone chemotherapy are more likely to have occult positive nodes at the time of surgery. ER positive pts and triple positive pts are also more likely to have occult positive nodes at time of surgery. While our sample is small, our breast PCR rate is consistent with other published literature. Further investigation confirming this with larger samples and multi-institutional investigation may help to establish these relationships and elucidate a predictive model. The optimal management of these patients is worthy of further study.
Citation Format: Rangel Melissa, Julia Alexieva, Alison Coogan, Elizabeth Marcus, Julie Wecsler. Predictive Factors of Nodal Upstaging at Time of Surgery in Clinically Node Negative Patients Undergoing Neoadjuvant Chemotherapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-02-10.