Potential utility of early metabolic response by 18F-2-fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography in a selected group of breast cancer patients receiving preoperative chemotherapy.

Introduction: To assess (18)F-2-fluoro-2-deoxy-d-glucose-positron emission tomography/computed tomography's ((18)F-FDG-PET/CT) potential clinical utility to allow early treatment changes during preoperative chemotherapy (PCT) in patients with early/locally advanced breast cancer (BC).

Patients And Methods: Sixty newly diagnosed early/locally advanced BC patients received 6-8 cycles of PCT. Optimal pathologic response (pR) was the absence of cancer cells in breast and axillary lymph nodes. All other conditions were defined as pathologic non-response (pNR). (18)F-FDG-PET/CT maximum standardised uptake value (SUV(max)) was measured at baseline and after 2 cycles of PCT. Metabolic response was defined as SUV(max) percentage changes (Δ-SUV) >50% and was compared with pR rates.

Results: Thirteen (22%) patients achieved pR; according to immunohistochemistry, 16% of ER-positive/HER2-negative patients, 29% and 27% of HER2-positive and triple negative patients respectively achieved pR. (18)F-FDG-PET/CT showed the highest specificity (38%) and negative predictive value (100%) in ER-positive/HER2-negative patients. In this subgroup, at a median follow-up of 36.6 months, median disease-free survival was still not reached in metabolic responders while it was 37 months in metabolic non-responders (p=0.049).

Discussion: Early metabolic non-response was always associated to pNR and poor prognosis in ER-positive/HER2-negative patients. In this subgroup, (18)F-FDG-PET/CT might be useful to select patients who will probably benefit from early therapeutic strategy modifications.