The Value of 18F-FDG PET/CT Imaging in the Evaluation of Interim Neoadjuvant Chemotherapy Response in Locally Advanced Breast Cancer.

Objectives:Neoadjuvant chemotherapy (NAC) is the frequently used treatment option for locally advanced breast cancer (LABC). This study investigated the potential value of 18fluorine-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) to estimate the pathological complete response (pCR) using maximum standardized uptake value (SUVmax) and change (ΔSUVmax) after 3-4 cycles of NAC. Additionally, it was established the relationship between PET/CT imaging findings and histopathological features in LABC patients whose treatment response was evaluated with interim PET/CT. Methods:Patients were evaluated with pretreatment and interim PET/CT scans and operated after on NAC. Data on the age of patients, menopausal status, tumor placement, histopathological and molecular subgroups were noted. SUVmax and ΔSUVmax of the primary tumor and axillary lymph node (ALN) were calculated from PET/CT review. Results:Pretherapy mean SUVmax of the primary tumor and ALNs were 8.13±4.25 and 7.22±3.58, respectively. The highest mean primary tumor ΔSUVmax and ALN ΔSUVmax values were observed to be human epidermal growth factor receptor 2 positivity (p<0.001). SUVmax-T, SUVmax-N, ΔSUVmax-T, and ΔSUVmax-N values were significantly correlated with the ki-67 index (p<0.001). ΔSUVmax-T and ΔSUVmax-N values of pCR (+) patients were statistically higher than the ΔSUVmax-T and ΔSUVmax-N values of pCR (-) patients (p<0.001). Conclusion:An earlier and more accurate response to NAC can be performed using interim 18F-FDG PET/CT imaging. ΔSUVmax levels of the breast tumor and ALNs may act as predictive for pCR in LABC patients receiving NAC.