Carcinoembryonic generally refers to carcinoembryonic antigen, also known as CEA. If this index gradually increases during the treatment process, it means that chemotherapy is not effective but ineffective or resistant to chemotherapy, as well as a sign of tumor progression. However, sometimes it also depends on whether the patient has other problems, for example, carcinoembryonic antigen is not only elevated in tumors, such as colon cancer or lung cancer, there are cases where this index is more elevated. Some benign lesions, such as colitis, can also lead to elevated carcinoembryonic antigen, so it is necessary to combine with other imaging examinations and endoscopy to observe the development of tumor lesions. The elevation of carcinoembryonic antigen alone cannot indicate the effectiveness of chemotherapy, but if the elevation is high, it indicates that chemotherapy may not be effective, and it is necessary to consider changing other regimens or combining targeted drugs and radiotherapy to treat the disease.