Use of ascitic CEA levels as a predictive value for distant metastasis in high-risk stage II and III colorectal cancer

Purpose: This study aimed to analyze the effect of ascitic carcinoembryonic antigen (CEA) levels on the long-term oncologic outcomes of colorectal cancer (CRC) following curative treatment. Methods: A total of 191 patients with stage II/III CRC were included. CEA was analyzed on the peritoneal fluid samples taken at the start of each surgery. Long-term oncologic outcomes were analyzed using known risk factors for recurrence in CRC. Result: Multivariate analysis of recurrence showed that lymphatic invasion (hazards ratio (HR) 2.7, 95% confidence interval (CI) 1.1–7, p = 0.038), vascular invasion (HR 2.8, 95% CI 1.2–6.3, p = 0.013), mucinous cancer (HR 3.6, 95% CI 1.3–10.1, p = 0.017), and peritoneal fluid CEA exceeding 5 ng/dl (odds ratio 3.1, 95% CI 1.2–7.7, p = 0.017) were significant risk factors. There were 14 patients with liver metastasis, 11 of whom had high ascitic CEA levels and no peritoneal metastasis. Additionally, eight had lung metastasis, and seven of them had high ascitic CEA levels. Conclusion: High ascitic CEA levels showed significantly lower disease-free survival and were significantly associated with distant metastasis in the lung and liver.