title: Effect of MR Imaging Contrast Thresholds on Prediction of Neoadjuvant Chemotherapy Response in Breast Cancer Subtypes: A Subgroup Analysis of the ACRIN 6657/I-SPY 1 TRIAL.
abstract: Functional tumor volume (FTV) measurements by dynamic contrast-enhanced magnetic resonance imaging can predict treatment outcomes for women receiving neoadjuvant chemotherapy for breast cancer. Here, we explore whether the contrast thresholds used to define FTV could be adjusted by breast cancer subtype to improve predictive performance. Absolute FTV and percent change in FTV (ΔFTV) at sequential time-points during treatment were calculated and investigated as predictors of pathologic complete response at surgery. Early percent enhancement threshold (PEt) and signal enhancement ratio threshold (SERt) were varied. The predictive performance of resulting FTV predictors was evaluated using the area under the receiver operating characteristic curve. A total number of 116 patients were studied both as a full cohort and in the following groups defined by hormone receptor (HR) and HER2 receptor subtype: 45 HR+/HER2-, 39 HER2+, and 30 triple negatives. High AUCs were found at different ranges of PEtand SERtlevels in different subtypes. Findings from this study suggest that the predictive performance to treatment response by MRI varies by contrast thresholds, and that pathologic complete response prediction may be improved through subtype-specific contrast enhancement thresholds. A validation study is underway with a larger patient population.
authors.affiliation: Departments of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California.
authors.forename: Wen
authors.initials: W
authors.lastname: Li
authors.affiliation: Departments of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California.
authors.forename: Vignesh
authors.initials: V
authors.lastname: Arasu
authors.affiliation: Departments of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California.
authors.forename: David C
authors.initials: DC
authors.lastname: Newitt
authors.affiliation: Departments of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California.
authors.forename: Ella F
authors.initials: EF
authors.lastname: Jones
authors.affiliation: Departments of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California.
authors.forename: Lisa
authors.initials: L
authors.lastname: Wilmes
authors.affiliation: Departments of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California.
authors.forename: Jessica
authors.initials: J
authors.lastname: Gibbs
authors.affiliation: Departments of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California.
authors.forename: John
authors.initials: J
authors.lastname: Kornak
authors.affiliation: Departments of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California.
authors.forename: Bonnie N
authors.initials: BN
authors.lastname: Joe
authors.affiliation: Department of Surgery, University of California San Francisco, San Francisco, California.
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Esserman
authors.affiliation: Departments of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California.
authors.forename: Nola M
authors.initials: NM
authors.lastname: Hylton
keywords: MRI; breast cancer; contrast enhancement; neoadjuvant