Positron emission mammography in the evaluation of interim response to neoadjuvant chemotherapy in patients with locally advanced breast cancer

Neoadjuvant chemotherapy (NAC) has an important role in patients with locally advanced cancers, treating distant micrometastases, downstaging tumors, improving operability, and sometimes allowing breast-conserving surgery to take place. We studied the association between two Positron Emission Mammography with 18F-FDG (18F-FDG-PEM) semi-quantitative parameters in 108 patients and correlated with pathologic response in each of the following breast cancer subtype: Triple negative breast cancer (TPN), HER2-positive, and ER-positive/HER2-negative cancers. Examine the association between two Positron Emission Mammography (PEM) semi-quantitative parameters: PUVmax (maximum uptake value) and LTB (lesion to background) baseline and the end of NAC with pathologic response in each breast cancer subtype. 108 patients, 71 with invasive ductal carcinoma and 37 with infiltrating lobular carcinoma were evaluate with 18F-FDG-PEM scans baseline and after end of NAC. We assessed the impact of 2 PEM semi-quantitative parameters for molecular subtype correlated with pathologic response according Miller-Payne grade (MPG). After NAC, an overall reduction of 2 PEM semi-quantitative parameters was found. Neither breast cancer subtypes nor Ki67 modified chemotherapy responses. Compared to PUVmax, an overall increase of LTB was found in baseline condition, independent of the expressed immunophenotype. Post-treatment values of PUVmax revealed a significant reduction compared to baseline values (4.8 ± 0.26 vs. 1.9 ± 0.18; p