BACKGROUND: Carbohydrate antigen 125 (CA-125) is commonly utilized as a tumor marker for ovarian cancer. However, CA-125 is also observed to be elevated in other malignancies such as lung cancer, liver cancer, pancreatic cancer, and thyroid cancer. The factors leading to elevated CA-125 levels and their implications are not entirely clear. Accumulation of case reports associated with elevated CA-125 will be instrumental in advancing research in this area. METHODS AND RESULTS: Here, we report a case involving a 45-year-old female patient diagnosed with Sigmoid Colon Adenocarcinoma. Laparoscopic pro-surgery CA-125 levels were 13.3 U/mL (reference range: <
35 U/mL), 12 days post-surgery CA-125 levels spiked to 132.3 U/mL, one month later CA-125 levels decreased to 73.5 U/mL, and three months later they returned to normal levels. Over a five-year follow-up period, there was no evidence of tumor recurrence or metastasis. CONCLUSIONS: Laparoscopic surgery induced a secondary elevation in CA-125 levels. The preoperative CA-125 level is more valuable for reference.