Pre-clinical studies in animals have translated to human benefit in breast cancer. A key example is the pharmaceutical tamoxifen, which has saved the lives of millions of people diagnosed with oestrogen receptor positive (ER+) breast cancer. Its approval as a clinical therapy was aided by elegant work with rodents conducted in the 1970s [1, 2]. This work also demonstrated the benefits of tamoxifen in breast cancer chemoprevention [3, 4]. Other examples resulting from initial pre-clinical studies in rodents include work leading to the development of trastuzumab [5, 6], and aromatase inhibitors [7, 8] as targeted therapies in clinical breast cancer. Results generated using in vitro models do not translate directly into clinical trials hence a stage of animal experimentation is involved in the development of novel breast cancer therapies. In addition, publication of studies in high-impact journals most often requires that data are verified in at least one (and sometimes in several) in vivo model. As an example,  used the MMTV-v-Ha-ras transgenic mouse model, developed originally by the Leder  and Jolicoeur groups  to examine the potential role of farnesyltransferase inhibitors on tumour regression. Similarly, the efficacy of dipyridamole in preventing breast cancer initiation, progression and metastasis was tested in MMTV-PyMT transgenic mice , which were developed originally by the Muller lab . Of these two examples (there are many more, as reviewed by ) both required extensive breeding programmes and subsequent hypothesis testing. Hence, a single project may involve the use of a large number of animals, each generating surplus tissues and other material that potentially could be utilised in future studies by other research groups.
Animal research includes syngeneic, xenograft and genetically modified (GEM) models. These are now an integral part of thousands of original publications each year, yielding significant advances across many research fields. However, this results in significant animal sacrifice; in 2013 alone, an estimated 20 million animals were used in scientific studies in the European Union and the United States. Scientists are encouraged to consider alternatives before embarking on new animal experiments, including due diligence on the validity of the model being considered in recapitulating human disease and/or phenotype, as well as employing the principles of the 3Rs—Replacement, Reduction and Refinement. The 3Rs were developed over 50 years ago as a framework for humane animal research  and is now part of national and international legislation regulating the use of animals in experiments. Not generally considered in this context is the potential wastage of surplus material from animal studies, or whether material is already available that can be used to answer the research question. Typically, research groups tend to collect materials from their projects, with the surplus sometimes being stored indefinitely, but also frequently being discarded at the end of the project. While the collection, storage, archiving and access policies for human clinical samples and transcriptomic data are routinely included in grant applications and often manuscript submissions, there is no obligation for investigators using animal models to do the same. This has economic, scientific and ethical shortcomings, resulting in considerable waste including duplication of experiments. This potentially lost material represents a valuable resource that could be used productively if there was a way for other researchers to identify it. Furthermore, if pre-existing models or materials were accessible elsewhere, obtaining these instead of recreating them would lead to fewer animals being used, as well as saving both time and money , illustrated schematically in Fig. 1. Currently, researchers lack the resources (money, databases, space, time) to generate and maintain systems that would catalogue their archival material and make it visible to other interested parties. SEARCHBreast therefore provides the missing link between those who have material available and those who would like to access existing samples, rather than repeating studies that have already been done. In particular, investigators without access to animal facilities may benefit from joining SEARCHBreast, providing them with an opportunity to carry out the type of studies that would increase the impact of their research.