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

ABSTRACT

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. AIM: 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. METHODS: 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). RESULTS: 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 ±â€¯0.26 vs. 1.9 ±â€¯0.18; p < 0.001) and LTB exhibited a significant decay after the first course of NACT (15.8 ±â€¯1.36 vs. 5.5 ±â€¯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), but if a correlation was found between the response rate by MPG and both semiquantitative parameters (p = 0.05). CONCLUSION: 2 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.