Generally speaking, patients with irritable bowel syndrome do not experience an increase in carcinoembryonic antigen (CEA) levels. An increase in CEA levels suggests the possibility of adenocarcinoma or precursor lesions of adenocarcinoma, which may not only be present in the intestines but also in the lungs and other tissues. In theory, tumor markers for patients with irritable bowel syndrome should be within the normal range. Once an increase in tumor markers such as carcinoembryonic antigen is observed, it is crucial to be highly vigilant about the possibility of adenocarcinoma, and it is necessary to actively complete related auxiliary tests, such as electronic colonoscopy, abdominal CT, chest CT, among others.