Elevated carcinoembryonic antigen 6 months after colon cancer surgery may be due to the presence of other cancers, incomplete resection of the tumor or metastasis, and the occurrence of benign diseases. It is recommended to follow medical advice regularly. 1. Suffering from other cancers: Carcinoembryonic antigen is one of the tumor markers, i.e. CEA, which increases when the patient suffers from colorectal, gastric, pancreatic and other tissues’ cancers. 2. Incomplete resection of tumor or metastasis: Elevated carcinoembryonic antigen after surgery may be due to incomplete resection of the tumor. In addition, recurrence or metastasis of the tumor may occur. Systemic chemotherapy may be received to kill metastatic or recurrent cancer cells. 3. Occurrence of benign diseases: such as hepatitis, pleurisy, biliary obstruction, etc., can also lead to transient elevation of carcinoembryonic antigen. At this time, symptomatic treatment and anti-inflammatory treatment can be carried out after examination and diagnosis. Patients should go to the hospital for examination in time and be treated under the guidance of doctors.