Usefulness of positron emission mammography in the evaluation of response to neoadjuvant chemotherapy in patients with breast cancer.

Our study examines 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 Neoadjuvant chemotherapy (NAC) with pathologic response in each of the following breast cancer subtype: Triple negative breast cancer (TPN), HER2-positive, and ER-positive/HER2-negative cancers. One-hundred and eight patients, 71 with invasive ductal carcinoma and 37 with infiltrating lobular carcinoma were evaluate with 18F-FDG-PEM scans before and after 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 < 0.001) and LTB exhibited a significant decay after the first course of NAC (15.8 ± 1.36 vs. 5.5 ± 0.49; P < 0.001). Using the Kruskal-Wallis H test which showed no correlation between the different molecular subtypes and the MPG and PUVmax and LTB (P = 0.52). Two PEM semi-quantitative parameters demonstrated a statically significant correlation and equivalence across the different breast cancer subtypes correlated with pathologic response according to MPG. PEM did not allow for prediction of NAC response in terms of breast cancer biomarkers, it is not discarded that this technology might be helpful for individual treatment stratification in breast cancer.