Retrospective analysis of preoperative tumor marker levels in rectal cancer patients: Implications for diagnosis.

Background: Early detection of rectal cancer poses significant challenges. Current diagnostic methods, including colonoscopy, imaging techniques, and fecal tests, have limitations such as invasiveness, cost, and varying sensitivity. This study evaluated the diagnostic value of preoperative serum tumor markers in rectal cancer patients.

Aim: To investigate the value of a multi-marker approach for the preoperative diagnosis of rectal cancer.

Methods: A retrospective analysis of 250 patients diagnosed with rectal cancer between July 2022 and July 2024 was conducted. Preoperative alpha-fetoprotein levels, carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), CA19-9, CA15-3, and CA72-4 were analyzed. All blood samples were collected under standardized conditions, including fasting status and proper storage methods, within two weeks before surgery. Diagnostic performance was assessed using receiver operating characteristic curve analysis. Correlations among clinicopathological features were also evaluated.

Results: CEA demonstrated the highest diagnostic performance among individual tumor markers with an area under the curve (AUC) of 0.78 [95% confidence interval (CI): 0.73-0.83]. However, a combination of CEA, CA19-9, and CA72-4 showed superior performance, achieving an AUC of 0.87 (95%CI: 0.83-0.91). Significant correlations were observed between CEA levels and several clinicopathological features, including tumor stage (P < 0.001), lymph node involvement (P = 0.002), and distant metastasis (P < 0.001). Furthermore, in a subgroup analysis of patients diagnosed after July 2022, the integration of fecal occult blood testing with the tumor marker panel (CEA + CA19-9 + CA72-4) significantly improved diagnostic accuracy, increasing the AUC to 0.91 (95%CI: 0.86-0.96).

Conclusion: A multimarker approach combining CEA, CA19-9, and CA72-4 with fecal occult blood testing enhances the preoperative assessment of patients with rectal cancer. These findings suggest potential improvements in risk stratification and management of patients with rectal cancer.