Association of quantitative MRI features of DCIS with surgical upstaging and recurrence after treatment.

e12540 Background: Ductal carcinoma in situ (DCIS) is a common preinvasive breast cancer typically identified on screening mammography. Pure DCIS is nonlethal, but 20-25% of DCIS cases identified on core biopsy upstage to invasive cancer at surgery and about half progress to invasive disease if not treated. As a result, most DCIS patients undergo excision and radiation therapy. DCIS score is a multigene assay that can aid in radiation treatment decision-making and serve as a surrogate marker of ipsilateral breast recurrence (IBR) risk. Breast MRI can accurately depict DCIS span and has potential to assess biology and IBR risk. We sought to assess the associations of advanced quantitative MRI features with upstaging and DCIS score. Methods: In this IRB-approved single institution prospective clinical trial, patients recommended for biopsy of calcifications or those who had residual calcifications after a biopsy yielding pure DCIS consented to receive a multiparametric breast MRI (dynamic contrast-enhanced and diffusion-weighted) prior to surgery. The following quantitative MRI features were obtained: functional tumor volume (FTV), volume transfer constant (K trans ), extracellular extravascular volume fraction (v e ), background parenchymal enhancement (BPE), and apparent diffusion coefficient (ADC). Patients with biopsy-proven DCIS were followed through completion of surgery to determine upstaging. DCIS score was performed in those with sufficient excision-proven pure DCIS. Associations of MRI features with invasive upstaging and DCIS score and were evaluated by Spearman’s correlation and the Wilcoxon rank-sum test. Results: Of the 120 patients enrolled in the study, 57 (48%) were diagnosed with pure DCIS on core biopsy. Fifty-five patients underwent surgery, 13 of whom (24%) upstaged to invasive disease. Thirty-eight pure DCIS lesions had sufficient tissue to generate a DCIS Score. Several MRI features were associated with upstaging and DCIS Score: K trans (p < 0.01) was significantly higher in lesions that upstaged to invasive disease. Higher DCIS scores were associated with lower K trans (p = 0.04) and v e (p = 0.05) values. No statistically significant associations were observed between FTV, BPE, or ADC and invasive upstaging or DCIS Score. Conclusions: This trial suggests advanced quantitative MRI features may help identify DCIS lesions at risk for upstaging to invasive disease and IBR. Specifically, an imaging feature of vascular permeability (K trans ) showed an expected positive association with upstaging. Imaging features of vascular permeability (K trans and v e ) showed counterintuitive inverse associations with DCIS Scores. Future research in larger cohorts is needed to validate these findings, better determine the biological reasons for these associations, and determine whether MRI features can be used clinically to optimize DCIS treatment. Clinical trial information: NCT03495011 .