Utility of FDG-PET/CT in the evaluation of the response of locally advanced breast cancer to neoadjuvant chemotherapy.

Neoadjuvant chemotherapy (NAC) is effective in down-staging a primary tumor before surgery, and quick differentiation between responders to NAC and nonresponders is needed. We investigated the utility of [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) and computed tomography (CT) in evaluating the therapeutic effectiveness of NAC. We investigated 25 patients who underwent NAC for stage II and III noninflammatory breast cancer. FDG-PET/CT was undertaken before and after NAC to determine the maximum standardized uptake value (SUVmax) reduction rate. Findings were compared with postoperative histopathologic evaluation of therapeutic response. It was not possible to accurately assess tumor response to NAC using CT. However, using the SUVmax reduction rate, we noted a significant difference (P=0.0420) between patients who were responsive and nonresponsive to NAC. The sensitivity and specificity were as high as 83.3% and 78.9%, respectively. This study demonstrated that FDG-PET/CT can differentiate responders from nonresponders. This improves patient management by avoiding unnecessary chemotherapy.