Complete Metabolic Response on Interim ¹⁸F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography to...

This study aims to investigate the prognostic role of complete metabolic response (CMR) on interim ¹⁸F-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.

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.

The median follow-up duration was 71 months. Maximum standardized uptake value (SUV_max) on an interim PET/CT independently correlated with survival by multivariate analysis (overall survival [OS]: hazard ratio: 1.139, 95% confidence interval: 1.058-1.226, p = .001). By taking PET timing into account, best association of SUV_max 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.

CMR indicated a significantly better outcome in BC and may serve as a favorable imaging prognosticator. 2017;22:526-534 IMPLICATIONS FOR PRACTICE: This study shows a significantly better outcome for breast cancer (BC) patients who achieved complete metabolic response (CMR) on ¹⁸F-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.