Consensus on the definition of locoregional recurrence of colon cancer: protocol for an international Delphi study

INTRODUCTION: Cancer recurrence is a pivotal outcome after treatment with curative intent for colon cancer patients, as it is related to worse survival, the subsequent need for further treatment and the associated use of healthcare resources. However, at present there is no consensus regarding the definition of locoregional recurrence of colon cancer. This contributes to variability in reporting outcomes and clinical management, limiting comparability across registries and clinical studies. This study aims to establish a consensus definition of locoregional recurrence using the Delphi method. METHODS AND ANALYSIS: We will conduct a worldwide Delphi consensus study among international experts involved in the treatment of colon cancer and recurrence (surgeons, medical oncologists, radiologists and pathologists). Conceptual elements of the survey were identified through literature exploration and concern: (i) anatomical locations, (ii) diagnostic criteria, (iii) resection margins and (iv) disease-free interval. Participants will be asked to rate their agreement on statements regarding the definition of locoregional recurrence of colon cancer. After the first round, we will analyse the data to determine which items have reached consensus for inclusion/exclusion and develop a second survey including items that did not reach consensus and any new items suggested by participants. ETHICS AND DISSEMINATION: The Dutch Medical Research Involving Human Subjects Act (WMO) does not apply to this study, as it does not involve patient participation. Participation is restricted to clinical health professionals. Results will be disseminated via communication to relevant societies in this field, presentations on (inter)national meetings and peer-reviewed publication.