Complete Metabolic Response on Interim 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography to Predict Long-Term Survival in Patients with Breast Cancer Undergoing Neoadjuvant Chemotherapy

BACKGROUND: F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) in patients with breast cancer (BC) receiving neoadjuvant chemotherapy (NAC) according to tumor subtypes and PET timing. PATIENTS AND METHODS: Eighty-six consecutive patients with stage II/III BC who received PET/CT during or following NAC were included. Time-dependent receiver operating characteristic analysis and Kaplan-Meier analysis were used to determine correlation between metabolic parameters and survival outcomes. RESULTS: with survival was obtained on PET after two to three cycles of NAC (area under the curve [AUC]: 0.941 at 1 year after initiation of NAC) and PET after four to five (AUC: 0.871 at 4 years), while PET after six to eight cycles of NAC had less prognostic value. CMR was obtained in 62% of patients (23/37) with estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2-) BC, in 48% (12/25) triple-negative BC (TNBC), and in 75% (18/24) HER2-positive (HER2+) tumors. Patients with CMR on an early-mid PET had 5-year OS rates of 92% for ER+/HER2- tumors and 80% for TNBC, respectively. Among HER2+ subtype, 89% patients (16/18) with CMR had no relapse. CONCLUSION: F-fluorodeoxyglucose emission tomography/computed tomography (PET/CT) during neoadjuvant chemotherapy, especially for hormone receptor-positive tumors and triple negative BC. Moreover, PET/CT performed during an early- or mid-course neoadjuvant therapy is more predictive for long-term survival outcome than a late PET/CT. These findings support that CMR may serve as a favorable imaging prognosticator for BC and has potential for application to daily clinical practice.