Abstract PD3-03: Determining the prognostic role of early and end-of-neoadjuvant chemotherapy 18F-FDG PET/CT in patients with locally advanced breast cancer

Abstract

Abstract Aim: To investigate the use of 18F-FDG PET/CT at diagnosis and after end-of-treatment in the prediction of response to neoadjuvant chemotherapy (NAC) and its role in the prognosis of patients with locally advanced breast cancer (LABC). Materials and Methods: One hundred thirty-two patients underwent a baseline FDG PET/ CT (PET-1) after the second course of chemotherapy (PET-2) and after the last course (PET-3). Breast tumors were classified into molecular phenotypes and grouped into risk categories according to the biological prognostic factors obtained by immunohistochemistry. PET/CT scans were semiquantitatively evaluated, obtaining the Δ% SUV1-2 and SUV1-3 in primary tumor and axillary lymph nodes to establish response groups attending to EORTC criteria. Moreover, a binary assessment was obtained classifying the studies as positive or negative. Pathological response was determined both in breast and axillary lymph node specimens. Overall survival (OS) and disease-free survival (DFS) were obtained during the follow-up. ROC analysis was performed to determine a cutoff value of Δ% SUV1-2 and SUV1-3 for the prediction of response and prognosis. Relations between molecular phenotypes, metabolic behavior, final pathological response, OS, and DFS were evaluated. This prospective and multicenter study was approved by the local ethics committee of our institution and included 7 hospitals of our region. Results: In binary analysis, only PET-3 was able to predict pathological response in lymph nodes. The cutoff values of %Δ SUV1-2 and %Δ SUV1-3 with the best sensitivity and specificity in the prediction of response in breast tumor were 62% (Se: 70% and Sp: 69%) and 84% (Se: 70%and Sp: 88%). A%ΔSUV1-3 of 74% in breast tumor was a predictor of DFS (AUC = 0.647; P = 0.037, Se: 52% and Sp: 66%). Kaplan- Meier analysis revealed significant relations between the binary lymph node assessment of PET-3 with OS (P = 0.016, χ2 = 5.78) and DFS (P = 0.003, χ2 = 9.10). Conclusions: Among the multiple metabolic response variables in breast tumor and lymph nodes, end-of-treatment 18F-FDG PET/CT was a significant predictor of breast and lymph node response and patient prognosis. The molecular phenotypes and pathological lymph node response rate were independent predictors of OS and DFS. This stresses the potential of the biological influence over metabolic variables in the prognosis of patients. Metabolic response variables work better in their predictive and prognostic value in high-risk tumors. Citation Format: Muñoz-Sánchez MdM, Molina-Garrido MJ, García Vicente AM, Soriano Rodríguez MdC, Amo Salas M, Olaverri Hernández A, Chacón Muñiz JI, Álvarez Cabellos R, Espinosa Aunión R, Ortega Ruipérez C, Martín Ordóñez F, Pena Pardo FJ, Jiménez Londoño GA, Val Pérez E, Santiago Crespo JA, Soriano Castrejón A. Determining the prognostic role of early and end-of-neoadjuvant chemotherapy 18F-FDG PET/CT in patients with locally advanced breast cancer [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 PD3-03.