Alpha-fetoprotein-producing advanced colorectal cancer: a rare case report and literature review.

Alpha-fetoprotein(AFP)-producing colorectal cancer is a rare form of colorectal cancer with a high degree of malignancy, advanced stage, strong invasiveness, poor response to treatment, rapid progression, and poor prognosis. Herein, we present the case of a middle-aged (in his 50s) male patient who underwent left neck lymph node biopsy due to "left neck lymph node enlargement for 5 months." Biopsy results revealed metastatic adenocarcinoma, and computed tomography examination of the chest and abdomen suggested a malignant tumor of the sigmoid colon with multiple metastases. Subsequently, the patient underwent colonoscopy, and the pathological result was colonic adenocarcinoma. Regarding tumor markers, serum alpha-fetoprotein (AFP) was 214 ng/mL. The patient received first- and second-line treatments for colon cancer, but progression-free survival was short. AFP was consistently elevated; after 8 months, the patient had AFP levels of 11,371.8 ng/mL, and imaging confirmed disease progression. The patient subsequently died, with an overall survival of more than 9 months. Compared with other tumor markers, AFP better reflects tumor progression in AFP-producing colorectal cancer.