Abstract P3-11-11: Prediction of treatment response to neoadjuvant chemotherapy in breast cancer by subtype using tumor-infiltrating lymphocytes: Study of a large Mexican cohort

Abstract

Abstract Background/aim: Tumor-infiltrating lymphocytes (TILs) are emerging as biomarkers mediating tumor response to treatments. Studies have provided evidence that the level of TILs has prognostic value in breast cancer. The level of TILs has been associated with treatment outcome and pathologic response in patients undergoing neoadjuvant chemotherapy. In this study, we analyzed TILs before neoadjuvant therapy and if they correlate with pathological response to treatment Patients and methods We retrospectively analyzed the specimen slides of patients with Breast Cancer from the Centro Oncologico Estatal ISSEMyM treated with Neoadjuvant Chemotherapy (NAC) during 2007–2014. We identified 410 patients fulfilling the inclusion criteria of this study. The histological sections had already been evaluated by hematoxylin and eosin slides. They were reassessed by our pathologist for the percentage of intratumoral and stromal TILs. The correlation with pathological response of the tumor after neoadjuvant therapy was also studied in these patients. The proportions of TILs were categorized into high and low groups using a cut-off value of 10% Resultados The mean age was 51.4 years. The most frequent type of breast cancer histology was invasive ductal breast carcinoma in 369 (90%) patients, 34 (8.3%) lobular and 1.7% other. The BC subtypes among the 410 patients who received NAC were TNBC in 82 (20%), HER2BC in 70 (17.1%), and HRBC in 258 (62.9%) patients. Treatment response was pCR in 164 (40%) and non-pCR in 245 (60%) patients. Based on subtype, pCR was achieved in 43 (52 %) patients with TNBC, 35 (50.0%) with HER2BC, and 87 (33%) with HRBC. There were 191 (46.5%) patients in the high-TIL group and 219 (53.5%) patients in the low-TIL group. Patients were divided into high-TIL and low-TIL groups, and the clinicopathological characteristics of each group were examined. High TILs that had a pathologically complete response were found in 56 % of patients, and low TILs were found in 44 %. There was a significant correlation between TILs and pathological response in patients with neoadjuvant chemotherapy (p = 0.04). Conclusion TILs may be a biomarker for predicting treatment response to NAC in patients with Breast Cancer. Studies assessing outcomes and therapeutic efficacies should consider. Citation Format: Campos Gomez S, Cabañas Chávez N, Hernández Alvarez J, Campos Gómez K. Prediction of treatment response to neoadjuvant chemotherapy in breast cancer by subtype using tumor-infiltrating lymphocytes: Study of a large Mexican cohort [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-11-11.