The prime advantage of CBR over the earlier proposed approaches is the intelligible reasoning process that leads to the systems diagnosis suggestion. A CBR-based CAD system reasons based on stored knowledge prior cases with associated ground truth and its final diagnosis suggestion is based on the ground truth of the stored cases that are most similar to the query case. Hence, its reasoning process is much easier to comprehend for the physician than an ANN system that acts like a black box. In this paper we propose a novel approach, based on decisiontree learning DT, for building a CAD system that predicts breast cancer biopsy outcomes based on BI-RADS compliant lesion descriptions. Similar to the cited CAD systems based on case-based reasoning, a CAD system based on decision trees features a very transparent reasoning process. However, in contrast to a CBR system, a decision-tree learner abstracts a global model of the decision process from the prior cases with associated ground truth instead of directly using these cases in the decision process. This global model is even easier to understand and predictions based on it are even easier to comprehend for the physician than those of a CBR system. In a second approach, we propose an extension of the state of the art CBR approaches that features an entropic distance measure. It provides a solid mathematical basis for measuring the similarity of cases that have attributes of different types e.g., nominal and numeric. It furthermore provides a clean mathematical foundation for handling missing attributes, in contrast to previous approaches.15 We have evaluated the proposed CAD approaches on two large, publicly available mammography databases to compare both their performance and features.