Quantitative molecular breast imaging for early prediction of neoadjuvant systemic therapy response in locally...

To evaluate the ability of quantitative molecular breast imaging (MBI) parameters obtained early during neoadjuvant systemic therapy (NST) in breast cancer patients to predict pathologic complete response (pCR) at surgery.

Patients with invasive breast cancer (T1-T4, N0-N3, M0) planned to receive NST followed by surgery were enrolled in a prospective Institutional Review Board approved trial (NCT #02324387). MBI was performed at baseline and after 2 cycles of NST. MBI images were quantified by drawing regions of interest over tumors to compute three quantitative MBI uptake metrics for correlation with pCR and residual cancer burden (RCB): MBI-specific standardized uptake value (SUV_MBI), tumor to background ratio (TBR), and tumor volume. MBI metrics were correlated with pCR and RCB using the Wilcoxon Rank Sum test or Fisher's exact test.

A total of 69 patients (median 48, range 30-77 years) were included in the analysis. Absolute decrease of 1.3 and 48% change of SUV_MBI was able to differentiate pCR vs nonpCR after 2 cycles of NST with AUC 0.76 and 0.77, and RCB 0/1 (response) versus RCB 2/3 (nonresponse) with AUC of 0.79 and 0.82, respectively. Absolute and percent changes in TBR were predictive of pCR and RCB with an AUC of 0.74 and 0.76, respectively.

SUV_MBI and TBR changes after 2 cycles of NST correlate with and may predict pCR in patients with locally advanced breast cancer. Quantitative MBI parameters are novel promising imaging biomarkers for early prediction of pCR optimizing management of NST in patients with breast cancer.