Pathologic Staging of Colorectal Adenocarcinoma: Changes and Updates in the American Joint Committee on Cancer (AJCC) 8th Edition and College of American Pathologists' Cancer Protocol

Abstract

Abstract The eighth edition of the AJCC Cancer Staging Manual has been published, and the new staging schemes will be applicable in 2018. The College of American Pathologists has also released an updated protocol incorporating these changes. While the overall T and N categories are similar to the seventh edition, the definitions of intramucosal adenocarcinoma, T4a category, and tumor deposits have been made more precise. The category of M1c has been created for peritoneal metastasis because of its worse outcome. In the College of American Pathologists protocol, tumor budding and venous invasion have been incorporated as recommended (optional) elements, the scoring of tumor regression has been updated, and the importance of screening for microsatellite instability/mismatch repair proteins has been emphasized. This review provides a brief description and rationale for these changes and updates.