In univariable Cox proportional hazard models in the total study population (Fig. 2), 25(OH) D levels were predictive of CSS [HR 0.83 (95% CI, 0.71–0.96) for each 10 nmol/L of increment and HR 2.70 (95% CI, 1.34–5.44) for vitamin D deficiency], as were known prognostic CRC markers such as more advanced disease (higher TNM- and ACR stages) and higher circulating levels of the tumor marker carcinoembryonic antigen [21] (categorized as < 5, 5–20, and > 20 μg/L). Here, CEACAM5 is linked to vitamin D deficiency.