Abstract P5-08-22: Impact of delay neoadjuvant chemotherapy on pathologic complete response in locally advanced breast cancer evidence of the real world in Mexico
Authors: Cabrera P , Muñoz W , Gutierrez L , Ramirez MT , Albarado A , Lara F , Mohar A 
Published: May 2019

Abstract
Background:
Several studies suggest that delay on initiation adjuvant systemic therapy has subtype specific effects on survival. Many patients need neoadjuvant chemotherapy (NAC) for locally advanced breast cancer (LABC) in middle income countries. The optimal timing from breast cancer (BC) diagnosis to initiation of NAC is unknown and is not known if this interval impacts in pathological complete response (pCR) and survival.
We evaluated the relationship between pCR (defined as no invasive disease in breast and lymph nodes) and the implications in survival outcomes from LABC diagnosis and initiation of NAC.
Methods:
Data were collected retrospectively from database on National Cancer Institute for locally advanced breast cáncer (II-III) treated with NAC within six months of their diagnosis and completed treatment between January 2007 to December 2015. We evaluated data´s of 934. Time between biopsy result and start of chemotherapy was calculated. Patients were grouped into those who had pCR vs. no pCR, those who started treatment within 28 days and those who started after 28 days and the expression of hormonal receptors and Her2 by immunohistochemistry. We evaluated the results with the Pearson´s X2 and Fisher´s exact test.
Results:
We evaluated data´s of 934 woman. Overall pCR rate for our population was (311) 33%. The patients who initiated their treatment before 28 days the pCR rate was 40% and in the group who initiated NAC after 28 days the pCR was 27% with p= 0.0001, independently of the immunohistochemistry pattern expression. The median overall survival for the patients who initiated NAC before 28 days is 111 months compare with the patients who initiated NAC after 28 days was 101 months with a p= 0.52. For disease free survival in patients who began NAC before 28 days and achieved pCR were 92.2 months and for the group after 28 days were 89.9 months (p=0.033)
If we divided the group in triple negative patients by immunohistochemistry (183) ER negative, PR negative, HER2 negative, the patients with less than 28 days have 49.5% of pCR and the patients who initiated NAC after 28 days have pCR 37% (p=0.044). In the group with triple positive 70 patients (ER positive, PR positive, HER2 positive) those who began the NAC before 28 days achieved pCR 45% and those after 28 days have pCR 39% (p=0.40). The patients with ER positive and HER2 negative 475, before 28 days achieved pCR 26% and those after 28 days pCR was 11% (p=0.0001). And finally the patients with ER negative and HER2 positive have a pCR of 64% if the NAC initiated before 28 days and the pCR was of 52% if the NAC started after 28 days (p=0.15).
Conclusions: As in the adjuvant treatment, the time between biopsy and initiation of neoadjuvant chemotherapy has an impact on the pCR rates and survival of patients with breast cancer locally advanced treated at National Cancer Institute of Mexico in the context of a real world scenario.
Citation Format: Cabrera P, Muñoz W, Gutierrez L, Ramirez MT, Albarado A, Lara F, Mohar A. Impact of delay neoadjuvant chemotherapy on pathologic complete response in locally advanced breast cancer evidence of the real world in Mexico [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 P5-08-22.