Peripheral monocyte count is associated with the risk of liver metastasis: A study of 7187 newly diagnosed patients with colorectal cancer.

Objective: To evaluate the effect of the absolute peripheral blood monocyte count (AMC) on the risk of synchronous colorectal liver metastasis (synCRLM).

Materials and methods: AMC as well as other baseline clinical characteristics between the synCRLM+ group (with synCRLM) and the synCRLM - group (without synCRLM) were measured. Taking AMC of 0.47 × 109/L as the cut-off value, the prevalence of synCRLM was compared between AMC-high level group (AMC ≥ 0.47 × 109/L) and AMC-low level group (AMC ≥ 0.47 × 109/L); significant predictors for synCRLM were analyzed by logistic regression analysis.

Results: The AMC value of the synCRLM- group was significantly lower than that in the synCRLM+ group. The difference was statistically significant (Mann-Whitney U test, Z = -6.546, P = 0.001). There was no significant difference in age, the primary site of tumor, and tumor size between the two groups. The prevalence of synCRLM in the AMC-low group was lower than that in the AMC-high group, and the difference was statistically significant (χ2 = 34.861, P = 0.001). At the same time, univariate and multivariate regression analyses showed that (elevated) AMC, eosinophil, basophil, triglyceride, alanine transaminase (ALT), alkaline phosphatase (ALP), carbohydrate antigen 19-9 (CA19-9), tumor stage, and distant metastasis status were risk factors of synCRLM, with AMC found to be an independent and the highest risk factor for synCRLM (hazard ratio [HR]: 1.455, [95% confidence interval {CI}: 1.012-2.093], P = 0.043).

Conclusion: In conclusion, elevated AMC is highly associated with an increased risk of colorectal liver metastasis (CRLM).