Prognostic Role of Early and End-of-Neoadjuvant Treatment 18F-FDG PET/CT in Patients With Breast Cancer

Aim: To determine the use of early and final treatment F-18-FDG PET/CT in the prediction of response to neoadjuvant chemotherapy (NAC) and its role in the prognosis of patients with locally advanced breast cancer (LABC). 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 categorized into molecular phenotypes and risk categories according to the biological prognostic factors obtained by immunohistochemistry. PET/CT scans were semiquantitatively evaluated, obtaining the Delta% 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. Histopathological response was obtained in breast and lymph node specimens. Overall survival (OS) and disease-free survival (DFS) were obtained after the follow-up. ROC analysis was performed to determine a cutoff value of Delta% SUV1-2 and SUV1-3 for the prediction of response and prognosis. Relations between phenotypes, metabolic behavior, final histopathological response, OS, and DFS were evaluated. Results: In binary analysis, only PET-3 was able to predict histopathological response in lymph nodes. The cutoff values of %Delta SUV1-2 and %. 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%Delta SUV1-3 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, chi(2) = 5.78) and DFS (P = 0.003, chi(2) = 9.10). Conclusions: End-of-treatment F-18-FDG PET/CT was a predictor of lymph node response and prognosis. Most of metabolic response variables related to histopathological response showed association with the prognosis.