Prognostic value of pretreatment serum carbohydrate antigen 19-9 level in patients with colorectal cancer: A meta-analysis

BACKGROUND Carbohydrate antigen 19-9 (CA 19-9) is one of the most frequently used tumor markers for gastrointestinal cancer, particularly for diagnostic purposes. However, its value in predicting prognosis remains controversial. In this study, we sought to clarify this by conducting a meta-analysis of relevant studies. METHODS We systematically searched several databases, including PubMed, EMBASE and Web of Science for articles pertaining to the relationship between pretreatment serum CA 19-9 levels and prognosis in patients with colorectal cancer (CRC). The reported hazard ratios (HR) of overall survival (OS), disease-free survival (DFS), pooled progression-free survival (PFS) and recurrence-free survival (RFS) in the analyzed studies were compared by fixed effects/random effects models. RESULTS Seventeen studies involving 6434 patients with CRC were included in our meta-analysis. A comprehensive analysis of the collected data revealed that high serum CA 19-9 levels before treatment were significantly associated with poor OS (HR: 1.58, 95% CI: 1.36-1.83, P<0.001), DFS (HR: 1.71, 95% CI: 1.38-2.13, P<0.001), PFS (HR: 1.30,95%CI:0.93-1.82, P = 0.121) and RFS (HR: 1.43, 95% CI: 1.11-1.83, P = 0.006). This association between high pretreatment serum CA 19-9 levels and poor survival held true across different geographical regions, analysis types, methods used for HR determination, sample size, and treatment methods. CONCLUSIONS The results of this study indicate that pretreatment serum CA 19-9 level can be used as a prognostic indicator for patients with CRC.