Clinical significance of combined testing of YKL-40 with CEA in Chinese colorectal cancer patients.

Background: To investigate the practical value of individual and combined testing of plasma levels of YKL-40, CEA, and CA199 for auxiliary diagnosis and detection of recurrence of colorectal cancer. Methods: ELISA and ECLIA were used to evaluate levels of YKL-40, CEA, and CA199 in 120 colorectal cancer patients (56 initial-diagnosis, 42 post-operative, and 22 recurrent cases). Forty-three patients with benign colorectal disease and 36 healthy patients were enrolled as controls. The relationship between YKL-40 and clinical indicators of tumor pathology was analyzed. The positive rate and diagnostic efficacy of single and combined YKL-40, CEA, and CA199 testing were assessed in patients with colorectal cancer. Results: Plasma YKL-40 in the cancer group was significantly higher than in the benign control and healthy control group, and the mean values were 145.4 ng/mL, 107.7 ng/mL, and 51.3 ng/mL (p < 0.05), respectively. With 72 ng/mL as the diagnostic threshold, the sensitivity and specificity of YKL-40 in colorectal cancer diagnosis were found to be 73.2% and 66.7%, respectively. Early-stage colorectal cancer patients showed a YKL-40 positive rate (73%) significantly higher than those of CEA and CA199 (50% and 32%, respectively; p < 0.05). When YKL-40 testing was combined with CEA or CA199, the positive rate increased to 82.1% and 80.3%, respectively. Through ROC curve analysis of the post-operative recurrent group against the non-recurrent group, the areas under the curve for YICL-40, CEA, and CA199 were found to be 0.907, 0.714, and 0.759, respectively. Based on the Dukes classification, the mean YKL-40 value for stages A/B, C, and D were 120.1 ng/mL, 131.7 ng/mL, and 226.8 ng/mL (p = 0.008), respectively. The plasma YKL-40 level gradually increased as the disease progressed. Lower degrees of tumor differentiation were correlated with higher YICL-40 levels. The mean YICL-40 values of high, medium, and low tumor differentiation groups were 96.8 ng/mL, 127.5 ng/mL, and 225.7 ng/mL (p = 0.004), respectively. Conclusions: The benefits of using YKL-40 testing are higher than CEA and CA199 for the monitoring of colorectal cancer recurrence. Combined testing of both YKL-40 and CEA was found to be optimal for auxiliary diagnosis of colorectal cancer. Plasma YKL-40 was found to be suitable for auxiliary diagnosis of colorectal cancer.