Caisis is an open source, web-based cancer data management system that integrates research with patient care. The system is freely distributed to promote standards and collaborative research, and has been downloaded by thousands of institutions world wide. Collaboration with multiple centers has allowed Caisis to develop and evolve in an environment of constant feedback and scrutiny. This community has shaped the features, usability, and overall vision of creating large, clean, unbiased datasets that will have a major impact on cancer research and patient care.