BACKGROUND

Serum calcium ion (Ca) is an economical and readily available indicator as a routine screening test for hospitalized patients. There are no studies related to serum Ca level and digestive tract malignancy.

AIM

To evaluate the effectiveness of serum Ca level in predicting the prognosis of patients with colorectal cancer (CRC).

METHODS

We retrospectively collected the data of 280 patients diagnosed with CRC who underwent radical surgery at the Affiliated Cancer Hospital of Xinjiang Medical University. By analyzing the clinicopathological features, differences between serum Ca concentrations on the first day after surgery were determined. We used the receiver operating characteristic curve to assess the predictive ability of serum Ca for survival. Survival analyses were performed using the Kaplan-Meier method, and multivariate Cox proportional risk regression was used to determine association between calibration serum Ca levels and CRC survival outcomes.

RESULTS

By receiver operating characteristic curve analysis, the ideal threshold value for Ca the first postoperative day and delta serum calcium (δCa) value were 1.975 and 0.245, respectively. Overall survival (OS) and progression-free survival (PFS) were better in both the high Ca group and high δCa group on the first postoperative day. The variables identified through univariate analysis were incorporated into multivariate analysis and showed that tumor differentiation ( = 0.047), T stage ( = 0.019), N stage ( < 0.001), nerve vascular invasion ( = 0.037), carcinoembryonic antigen ( = 0.039), baseline serum Ca level ( = 0.011), and serum Ca level on the first day ( = 0.006) were independent predictors of prognosis for patients undergoing feasible radical CRC surgery. Using the findings from the multifactorial analysis, we developed a nomogram and the calibration showed a good predictive ability.

CONCLUSION

Low serum Ca level on the first postoperative day is an independent risk factor for OS and PFS in CRC.