Significance and Correlation Analysis of Folate Receptor-Positive Circulating Tumor Cells (FR + CTC) in Colorectal Cancer Patients.

[BACKGROUND] To investigate the significance of detecting folate receptor-positive circulating tumor cells (FR + CTC) in colorectal cancer patients and to analyze their correlation with the expression of conventional tumor markers (CEA, CA199, CA125).

[METHODS AND RESULTS] A retrospective collection of preoperative FR + CTC values from patients in the Gastrointestinal Surgery Department of Henan Provincial People's Hospital between July 2021 and May 2023 was conducted. The area under the ROC curve was used to assess the accuracy of FR + CTC values and the expression levels of conventional tumor markers (CEA, CA199, CA125) in diagnosing colorectal cancer patients with peritoneal metastasis, lymph node metastasis, vascular invasion, nerve invasion, and tumor penetration of the serosal layer (T3-4). Spearman correlation analysis was used to study the correlation between FR + CTC values and the expression levels of CEA, CA199, and CA125. Non-parametric tests were used to study the differences in CTC values, CEA, CA199, and CA125 among different types of colorectal cancer patients. A total of 273 colorectal cancer patients with preoperative FR + CTC detection were included in the study. Among these, 19 patients (7.0%) had peritoneal metastasis. The areas under the ROC curve for diagnosing colorectal cancer patients with peritoneal metastasis, lymph node metastasis, vascular invasion, nerve invasion, and tumor penetration of the serosal layer (T3-4) using FR + CTC were 0.828, 0.617, 0.651, 0.642, and 0.622, respectively, all of which were higher than those of conventional tumor markers (CEA, CA199, CA125). The optimal FR + CTC cut-off value for diagnosing peritoneal metastasis was 14.0 FU/3 mL, with a sensitivity of 80.5% and a specificity of 85.2%. There was a statistically significant correlation between FR + CTC values and CA125 expression levels (correlation coefficient R = 0.15, p = 0.015), while no significant correlation was found between FR + CTC values and the expression levels of CEA and CA199. The detection values of FR + CTC were higher in colorectal cancer patients with peritoneal metastasis, lymph node metastasis, vascular invasion, nerve invasion, and tumor penetration of the serosal layer (T3-4), with statistically significant differences (p < 0.05).

[CONCLUSION] FR + CTC values can serve as a new tumor marker for colorectal cancer patients, offering stronger clinical guidance than traditional gastrointestinal tumor markers (CEA, CA199, CA125). Future research should focus on validating these results in multicenter prospective cohorts and exploring the integrative value of FR + CTC with other liquid biopsy markers like ctDNA.