We explore a compositional breast imaging technique known as three compartment breast (3CB) to improve malignancy detection. The addition of 3CB compositional information to computer-aided detection (CAD) software improved malignancy predictions resulting in an area under the receiver operating characteristic curve (AUC) of 0.81 (confidence interval (CI) of 0.74-0.88) on a held-out test set, while CAD software alone achieved an AUC of 0.69 (CI 0.60-0.78). We also identified that invasive breast cancers have a unique compositional signature characterized by reduced lipid content and increased water and protein content when compared to surrounding tissues. Clinically, 3CB may potentially provide increased accuracy in predicting malignancy and a feasible avenue to explore compositional breast imaging biomarkers.