18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) as early imaging biomarker of axillary sentinel lymph node (SLN) status in locally advanced node-positive breast cancer (NPBC) patients (pts) receiving neoadjuvant chemotherapy (NACT).

1129 Background: Use of FDG-PET in the early evaluation of NACT for NPBC is currently under investigation. The aim of this study is to assess FDG-PET in NPBC pts receiving NACT in order to identify a subset of pts that can be spared axillary lymph node dissection (ALND) in case of response. Methods: All pts (period 2009-2011) had [cT2 (≥3cm)-T4, pN1-3], and no prior BC treatment. All pts received 8 cycles (cy) of NACT +/- trastuzumab. FDG-PET was performed at baseline and after 2 cy. After NACT, mastectomy with SLN and ALND was peformed. As primary endpoint, the change in maximum standardized uptake value (SUVmax) in the primary tumor (PT) and ALNs was compared with pathological response (Jonckheere-Terpstra test). Logistic regression was used to determine the predictive value of a 50% reduction in SUVmax on pathological response and SLN status. Results: Forty-one pts were evaluable for the primary endpoint and 31 pts had successful SN procedures. The median age was 49.8 years (range 27-75). Overall, 9.8%...