BACKGROUND: This study aimed to evaluate the predictive value of serum levels of methylenetetrahydrofolate reductase (MTHFR) and carcinoembryonic antigen (CEA) for tumor size reduction following neoadjuvant CAPEOX chemotherapy in patients with advanced colorectal cancer. METHODS: A prospective observational study was conducted involving 36 patients with histologically confirmed stage III-IV colorectal cancer who underwent neoadjuvant CAPEOX therapy. Serum MTHFR and CEA levels were measured before chemotherapy. Tumor response was assessed by comparing pre- and post-treatment imaging, based on RECIST criteria. Correlations between the biomarkers and the percentage of tumor reduction were analyzed using Spearman's test, followed by multivariate linear regression to develop a predictive model. RESULTS: The mean age of participants was 45.6 ± 8.0 years, with a predominance of male patients (66.7%). Both serum MTHFR and CEA levels showed significant correlations with tumor size reduction (MTHFR: ρ = 0.764, p < 0.001; CEA: ρ = 0.654, p < 0.001). The final regression model demonstrated strong predictive performance: Tumor size reduction (%) = -165.68 + (1.10 × CEA) + (15.38 × MTHFR), with an adjusted R² of 0.714 (p < 0.001). A nomogram derived from this model yielded a Harrell's C-index of 0.836, indicating high discriminative ability in predicting therapeutic response. CONCLUSION: Serum MTHFR and CEA levels serve as complementary biomarkers for predicting tumor size reduction following neoadjuvant CAPEOX chemotherapy in advanced colorectal cancer. Their combined use provides a simple, cost-effective tool for individualized treatment planning and advances biomarker-based precision oncology in resource-limited clinical settings.
Cahyopoetro et al. (Fri,) studied this question.