High serum levels of both carcinoembryonic antigen and carbohydrate antigen 19-9 in a patient with sigmoid colon cancer without metastasis

Carcinoembryonic antigen (CEA) and carbohydrate antigen (CA)19-9 are well known as the most common tumor markers of colon cancer, and levels are used not only for preoperative assessment of extent and outcome of cancer, but also postoperative monitoring of recurrence. We encountered a patient with sigmoid colon cancer showing abnormally high serum levels of CEA (311.1 ng/ml) and CA19-9 (5731.2 U/ml) preoperatively. We could not detect any metastases on computed tomography (CT) or 18F-fluorodeoxyglucose positron emission tomography/CT. Sigmoidectomy and lymph node dissection were performed. Pathological analysis revealed well-differentiated tubular adenocarcinoma of the sigmoid colon with cancer cells infiltrating to the subserosa, but no lymph node metastases. As of postoperative day 60, serum levels of CEA and CA19-9 were 3.4 ng/ml and 9.2 U/ml, respectively, without any further anti-tumor treatment. This represents a rare case of sigmoid colon cancer with high levels of tumor markers in sera that improved following sigmoidectomy without further anti-cancer treatment.