The Collaborative Stage Data Collection System (CS), used to collect cancer information and derive stage values, was extensively revised in response to revisions in the American Joint Committee on Cancer's AJCC Cancer Staging Manual seventh edition, published in 2010. CSv2 was released to the cancer registry community for use in January 2010. In February 2010 the CSv2 Project management team authorized the data validation project to review the content and formatting of the data tables and make recommendations to the CSv2 mapping team for modifications to the tables. This article describes the review process, problems identified and resolved, and results: 1453 new codes, 340 converted codes, 301 codes marked for manual review, 6 new types of data tags, 3 new version numbers, changes in table notes, changes in construction of intermediate tables, and changes in tables which combine AJCC TNM components into stage assignments. The purpose of this article is to help software vendors, registry users, and data analysts understand the changes they will see as they implement the new version, CSv2:V0203. Also, as vendors, users, and analysts become aware of the complexities and limitations of the current system and processes, and the considerations involved in modifying the system, evident to those working on the project, it is hoped that the review presented in this article will inform ongoing discussions about the future management and development of the Collaborative Stage Data Collection System.